Author: exarkun
Revision Date: 2010-04-13 15:53:04 UTC

Merge pyflakes-ast-3005

Author: gbrandl, exarkun
Reviewer: exarkun
Fixes: #3005

Convert pyflakes to use the Python 2.5+ _ast module instead of
the older (now essentially unmaintained) compiler package.

Introduce a number of new tests for various edge cases previously
untested, as well, since this involved changing substantial chunks
of pyflakes internals.

Also add support for certain new constructs which will be added
in Python 2.7, including set comprehensions and dict comprehensions.

Because Python 2.4 does not include the _ast module, this change
effectively drops support for running Pyflakes using Python 2.4.