and ignore gevent/util_py2.py

based on #362 by @fantix

Added __bool__ for PY3 next to __nonzero__.

Remove test_support.py

Port gevent vfd to win64

Since long on win64 is 32-bit it cannot hold all possible
SOCKET handle values, making it theoretically possible to
get an exception "OverflowError: Python int too large to
convert to C long" if socket handles become too big. Now
on win64 it properly uses PY_LONG_LONG.

Refs #38, fix pywsgi headers issue in PY3

Ignore sys.exc_clear() for PY3.

Fix indexing exceptions (ex[0]) by using args (ex.args[0]), refs #38

Refs #38, fixed renamed symbols in PY3

Fix links for examples (docs gevent servers)

Fixed exec, refs #38.

Replaced execfile() with exec(open().read()) in gevent/monkey.py.

upgrade libev to 4.15

This should fix #361.

not needed since 2.5 is not supported anymore.

- do not swallow syntax errors
- make pyflakes.py py3-compatible #38
- run using specific version of python (previously pyflakes from the default python
  was used, which caused it to ignore py3-specific and py2.6-specific syntax errors

Previously pep8 and pyflakes were installed using the default system Python.
This changes 'make travis' to use the current Python version for those scripts as well.
This affects pep8, at least: on Python3 it complains about space in `print (...)`.

Handle renaming of "thread" to "_thread" in PY3

Use six.xrange in tests.