[Distutils] PEP 440 (versioning) nearing completion (I hope)

[Vinay Sajip]

Nick Coghlan <ncoghlan <at> gmail.com> writes:

> - a reference implementation (I'm hoping Vinay will be willing to step
> up to the plate with distlib again on that front)

First cut, done :-)

I updated distlib's implementation to:

- include the local component in NormalizedVersion
- allow single numeric component versions in NormalizedVersion
- update the NormalizedMatcher to include it in matches when required
- convert between - and _ in the version for the wheel filename

I've added/updated tests for these changes, but additional reviews/test 
results are always welcome.

Regards,

Vinay Sajip