Fix bug on Windows where ${CHECKFILE_ABS_PATH} was used inside a regex.

When this happened on Windows we would substitute in a path containing
"\" which would be interpreted as a regex escape which would break
parsing of the regex.

Switched to using a different method for generating the script used as a

entry point into the tool.

The previous method works fine on Linux but on Windows we get a script
that cannot be executed directly from the command line (we have to
prepend the python executable). This new method generates an entry point
script on Linux and on windows it actually generates a .exe file as
entry point so the tool can be run directly from the command line :)

I've switched from distutils.core to setuptools to squash the warning I
was getting about entry_points being ignored. Despite that it was still
working correctly on distutils.

Note I've still kept bin/OutputCheck because the testing framework still
depends on it and its nice to have a script I can run directly in the
repo.

Properly fix packaging problem for Python3. On download via pip

we would fail because str has no .decode() method.

Fixed bug where the --file-to-check command line argument could

not be parsed. A test case has been added for this bug.

Reformatted license so width does not exceed 80 characters.

Fixed missing description in setup.py