Most interesting: Use newer CPython API on Python 3, resulting in a 1.5x speedup.

Switched to a standard URL.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

This guarantees for the package feeds that
the mk files will always be available for all packages.

Will need to see about external-feed Python packages
a bit later.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Signed-off-by: Daniel Golle <daniel@makrotopia.org>