'--help-commands' option).
Shuffled imports around in a few command modules to avoid expensive
up-front import of sysconfig (and resulting delays in generating list
of all commands).
Added 'nuke_release_tree()' method to blow away the directory from
which the archive file(s) are created, and call it (conditionally)
from 'make_distribution()'.
Added 'keep_tree' option (false by default) to disable the call to
'nuke_release_tree()'.
Now supports the full range of intended formats (tar, ztar, gztar, zip).
"-f" no longer a short option for "--formats" -- conflicts with new
global option "--force"!
Greg Ward