createrepo development work

I've been checking in a lot of changes to HEAD of the createrepo git
repo this week. I've not modified the maintenance branch (which is where
all the 0.4.XX releases can come from). My rough road map for the new
createrepo looks like this:

1. convert it over to using yum package objects for handling the local
files
2. restructure everything so that createrepo can more easily be imported
and used by 3rd party tools
3. clean up the godforsaken mess that genpkgmetadata.py has become while
trying to make all the features continue to work.
4. make sure that adding package types (like debs) is easy enough to

Right now I've gotten 1 done (more or less) and 2 is well started. 3 is
happening mostly b/c I'm removing all the code out of genpkgmetadata as
I try to correct the program structure.

If anyone has some input or patches, let me know.

Thanks,
-sv