Update release date as well

For our Legacy API users, StyleGuide.init_report should reset the
formatter attribute before calling Application.make_formatter().

Closes #200

Re-allow for relative paths for exclude

*Description of changes*

Use the directory that the configuration file is found in as the parent (instead of the current working directory) when normalizing paths.

*Related to:*  #194

See merge request !109

Previously, all testing was done from the directory in which the
configuration file lived, so this bug went unnoticed. However, if you
run Flake8 against its own source from a directory above, you would
notice that the patterns in the exclude config value in tox.ini were
ignored. This is because we (like any reasonable person) are using
relative paths. The path is relative, however, to the directory in
which the configuration file was located. So we keep track of which
directory that is and use that to normalize the paths in the config
file.

Yes, there is an unrelated change to our tox.ini in this commit as
well. ;-)

Closes #194

Open our output file in append mode always

*Description of changes*

*Related to:*  #193

See merge request !108

This avoid overwriting portions of our log output when using Flake8
in verbose mode.

Closes #193

Test loading non-callable plugins

*Description of changes*

This is just a simple addition to prevent a regression regarding bug #164 and merge request !101.

*Related to:*  #164, !101

See merge request !106

Fixes #199: Report errors when run via setuptools.

*Description of changes*

*Related to:*  (Add bug number here)

See merge request !107

Closes #199

Add 3.0.3 release note about GitLab#164

Add 3.0.3 release note about #164

See merge request !103

With d234f22e it did not load plugins which aren't callable. This is adding a
basic test to it.

Diable multiprocessing behaviour on Windows

*Description of changes*

Due to https://bugs.python.org/issue27649, while Flake8 can *run* with multiprocessing on Windows, it does not behave as we expect it to behave. To provide the best experience that is in agreement with our documentation, we must disable multiprocessing until https://bugs.python.org/issue27649 is fixed and released.

Closes #184

See merge request !105

Due to https://bugs.python.org/issue27649, we cannot continue to
expect multiprocessing to work as we expect and document it on Windows.
As such, we are going to revert back to our previous behaviour of
disabling it across all versions of Python on Windows to provide the
default expected behaviour of Flake8 on that Operating System.

Allow plugins that are on by default to be ignored

*Description of changes*

Previously, users were unable to ignore the error code of a plugin that was on by default. This adds a tiny bit of extra logic to re-enable that behaviour.

*Related to:*  #195

See merge request !104

Previously, to ensure that plugins on by default were reported, we
added them to the select list. This means that ignoring them became
impossible. To accomodate our reporting logic and a user's ability
to ignore, we need to keep our select and extended select lists
separated.

This allows us to have a better understanding of who is selecting what,
where, and how and make our decision as to whether or not an error
should be reported more wisely.

Closes #195

Fix hyperlink in Links.



See merge request !102

Raise exception when entry_point not callable

Raise exception when entry_point not callable

E.g.:

```
$ .tox/flake8/bin/flake8 mobileweb
Traceback (most recent call last):
  File ".tox/flake8/bin/flake8", line 9, in <module>
    load_entry_point('flake8', 'console_scripts', 'flake8')()
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/cli.py", line 16, in main
    app.run(argv)
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/application.py", line 316, in run
    self._run(argv)
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/application.py", line 299, in _run
    self.initialize(argv)
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/application.py", line 289, in initialize
    self.find_plugins()
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/application.py", line 143, in find_plugins
    self.check_plugins.load_plugins()
  File "/Users/marca/dev/git-repos/flake8/src/flake8/plugins/manager.py", line 375, in load_plugins
    plugins = list(self.manager.map(load_plugin))
  File "/Users/marca/dev/git-repos/flake8/src/flake8/plugins/manager.py", line 267, in map
    yield func(self.plugins[name], *args, **kwargs)
  File "/Users/marca/dev/git-repos/flake8/src/flake8/plugins/manager.py", line 373, in load_plugin
    return plugin.load_plugin()
  File "/Users/marca/dev/git-repos/flake8/src/flake8/plugins/manager.py", line 173, in load_plugin
    raise failed_to_load
flake8.exceptions.FailedToLoadPlugin: Flake8 failed to load plugin "P999" due to Plugin <module 'teamcity.flake8_plugin' from '/Users/marca/dev/git-repos/teamcity-messages/teamcity/flake8_plugin.pyc'> is not a callable. It might be written for an older version of flake8 and might not work with this version.
```

This is nicer than the previous behavior of raising an obscure `PicklingError` and then hanging.

```
$ .tox/flake8/bin/flake8 mobileweb
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/queues.py", line 268, in _feed
    send(obj)
PicklingError: Can't pickle <type 'module'>: attribute lookup __builtin__.module failed
```

*Related to:*  164

See merge request !101

E.g.:

```
$ .tox/flake8/bin/flake8 mobileweb
Traceback (most recent call last):
  File ".tox/flake8/bin/flake8", line 9, in <module>
    load_entry_point('flake8', 'console_scripts', 'flake8')()
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/cli.py", line 16, in main
    app.run(argv)
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/application.py", line 316, in run
    self._run(argv)
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/application.py", line 299, in _run
    self.initialize(argv)
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/application.py", line 289, in initialize
    self.find_plugins()
  File "/Users/marca/dev/git-repos/flake8/src/flake8/main/application.py", line 143, in find_plugins
    self.check_plugins.load_plugins()
  File "/Users/marca/dev/git-repos/flake8/src/flake8/plugins/manager.py", line 375, in load_plugins
    plugins = list(self.manager.map(load_plugin))
  File "/Users/marca/dev/git-repos/flake8/src/flake8/plugins/manager.py", line 267, in map
    yield func(self.plugins[name], *args, **kwargs)
  File "/Users/marca/dev/git-repos/flake8/src/flake8/plugins/manager.py", line 373, in load_plugin
    return plugin.load_plugin()
  File "/Users/marca/dev/git-repos/flake8/src/flake8/plugins/manager.py", line 173, in load_plugin
    raise failed_to_load
flake8.exceptions.FailedToLoadPlugin: Flake8 failed to load plugin "P999" due to Plugin <module 'teamcity.flake8_plugin' from '/Users/marca/dev/git-repos/teamcity-messages/teamcity/flake8_plugin.pyc'> is not a callable. It might be written for an older version of flake8 and might not work with this version.
```

This is nicer than the previous behavior of raising an obscure `PicklingError` and then hanging.

```
$ .tox/flake8/bin/flake8 mobileweb
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/queues.py", line 268, in _feed
    send(obj)
PicklingError: Can't pickle <type 'module'>: attribute lookup __builtin__.module failed
```

See #164

Sort reports by line and column

*Description of changes*

The reports have been incorrectly sorted. This fixes the sorting order to use the line number and then column. It also adds a test to verify that the sorting algorithm works.

*Related to:*  #196

See merge request !100

Originally the reports have been sorted by column and message (without the
error code), so it didn't order after the line number.

Closes #196

Match noqa for users with explanations

*Description of changes*

*Related to:*  #178

See merge request !99

This makes the regular expression a bit more complex, and potentially
slower, but it will fix the issue where users had noqa comments with
colons followed by explanations.

Closes #178

Plugins do not have their parameters checked in advance, so when we
try to aggregate parameters for a plugin, there's a chance it may
request an attribute of the FileProcessor that simply does not exist.

We catch this and re-raise it but we should also capture it in the
checker manager and handle it appropriately there as well.

Fix multiprocessing on Windows

*Related to:*  #184 

I'm still running into #179 with this fix but all processes start now at least.

BTW the current design is pretty bad regarding memory footprint and bootstrap time as you have to pickle the manager object for *every* subprocess. So this does not only fix multiprocessing on Windows. It improves the multiprocessing design on other platforms, too.

See merge request !97

Fix read_lines_splits_lines test for CRLF endings

This change makes the test pass for when files are saved with CRLF Windows-style line endings since those are included in various `.readlines()` methods by default.

See merge request !96

_job_count always returns an int

Trivial change, but `_job_count` always returns an `int`.

See merge request !95

As FichteFoll pointed out on IRC, this line could include Python 3s
less than 3.2 as well.

Clarify what the X in the entry points does

*Description of changes*

Previously the `X` wasn't further explained in the documentation on how to
register a plugin. This plugs the hole at least for checking plugins.

*Related to:*  #183

See merge request !93

When attempting to centralize all inline NoQA handling in the StyleGuide
we inadvertently broke plugins relying on it in combination with checker
state. For example, the check for E402 relies both on NoQA and the state
to determine if it has seen a non-import line. Placing NoQA on the sole
line that is not an import is more elegant than placing it on each of
the following import lines.

Closes #186

We accidentally changed column numbering from one-indexed to
zero-indexed.

Update our flake8 testenv dependencies

*Description of changes*

Uncap Flake8 and add a lower bound to flake8-import-order

*Related to:*  N/A

See merge request !94

We had capped Flake8 until flake8-import-order created a new release. We
can now add a lower bound to flake8-import-order and uncap Flake8.