Bump version to 2.5.0 for release

Allow W605 to be silenced by noqa

Add check for over-indented blocks

Use 'dist: xenial' in Travis to simplify configuration

Allows using Python version 3.7 without sudo declarations.

Travis officially added support for Xenial on 2018-11-08.

https://blog.travis-ci.com/2018-11-08-xenial-release

In a project with all lines indented 4 spaces, I noticed pycodestyle was
not catching code that was accidentally indented two levels (8 spaces).
The over indentation was unintended and can be caught during static
analysis.

Fixes #430

Allow omitting blank lines around one-liner definitions.

fix #811, corner cases for async/await check

Correct ReStructuredText inline literal syntax in CONTRIBUTING.rst

* Test for whitespace around -> operator

Tests will pass after fixing issue #803

* Require whitespace around -> operator

Closes: #803

* Move tests to correct cases

* Whitelist python3 only tests

* Fix whitespace test errors

Huge thanks to @asottile!

* Address code review

Pushing this directly to run full testsuite on travis

* :bug:Change error code to space around bitwise operator E227

* Check for -> annotation only in py3.5+

* Skip tests meant for higher versions of python

* Move type annotation tests to python3.5 testsuite

Type annotations were first introduced in PEP 484,https://www.python.org/dev/peps/pep-0484/ implemented in python3.5

* Shorten line skipping tests by version

* Replace test skipping logic

As requested in code review

* Run formatting to avoid long lines

refs W606, only NAME can follow await

await NUMBER or await STRING is not valid syntax

Keep compability with stdlib tokenize.py changes

Make W605 point to the invalid sequence

str.count() can limit the counting to a range of string positions.

Instead of having W605 point to the beginning of the string literal,
make it point to the precise line and column of the invalid escape sequence.

This is more helpful when you have multiline string literals.

Fix some spelling in CONTRIBUTING.rst

Add testing and document support for Python 3.7

Fix line offset for 'invalid escape sequence'

https://github.com/python/cpython/commit/c4ef4896eac86a6759901c8546e26de4695a1389
is not yet part of any release of Python but has been backported to all
versions in Git (includeing 2.7!). It causes the tokenize.py module to
emit a synthetic NEWLINE token for files that do not in fact end with a
newline, which confuses pycodestyle's checks for blank lines at the end
of a file. Fortunately the synthetic NEWLINE tokens are easy to detect
(the token text is "").

Fixes #786

Remove suggestion and documentation of using unmaintained nose

The nose project has ceased development. The last commit is from Mar 3,
2016. From their docs page:

https://nose.readthedocs.io/

> Note to Users
>
> Nose has been in maintenance mode for the past several years and will
> likely cease without a new person/team to take over maintainership.
> New projects should consider using Nose2, py.test, or just plain
> unittest/unittest2.

Python 3.7 was released on June 27, 2018.

https://docs.python.org/3/whatsnew/3.7.html

Comment spelling fix

Update all pypi.python.org URLs to pypi.org

For details on the new PyPI, see the blog post:

https://pythoninsider.blogspot.ca/2018/04/new-pypi-launched-legacy-pypi-shutting.html

Remove support for EOL Python 2.6 and 3.3

Python 2.6 an 3.3 are end of life. They are no longer receiving bug
fixes, including for security issues. Python 2.6 went EOL on 2013-10-29
and 3.3 on 2017-09-29. For additional details on support Python
versions, see:

https://devguide.python.org/#status-of-python-branches

Removing support for EOL Pythons will reduce testing and maintenance
resources. Removed all workarounds for older Pythons.

Updated trove classifiers and documentation to better communicate
supported Python versions.

Additionally, pass python_requires argument to setuptools. Helps pip
decide what version of the library to install.

https://packaging.python.org/tutorials/distributing-packages/#python-requires

> If your project only runs on certain Python versions, setting the
> python_requires argument to the appropriate PEP 440 version specifier
> string will prevent pip from installing the project on other Python
> versions.

https://setuptools.readthedocs.io/en/latest/setuptools.html#new-and-changed-setup-keywords

> python_requires
>
> A string corresponding to a version specifier (as defined in PEP 440)
> for the Python version, used to specify the Requires-Python defined in
> PEP 345.

Can now use more modern Python syntax including dictionary comprehension
as well as more generators.

Closes #755

Change the position pointed out by W504