PEP 370 features and sys.dont_write_bytecode are always available
in 3.3; the distutils2 backport still has the conditionals.
I also renamed an internal misnamed method and fixed a few things
(“packaging2” name, stray print, unused import, fd leak).
These options were used to implement “setup.py --name”,
“setup.py --version”, etc. which are now handled by the pysetup metadata
action or direct parsing of the setup.cfg file.
As a side effect, the Distribution class no longer accepts a 'url' key
in its *attrs* argument: it has to be 'home-page' to be recognized as a
valid metadata field and passed down to the dist.metadata object.
I cleaned up some comments, docstrings and code along the way.