Upstream changes:
0.04 2010-06-13
get_package_symbol now doesn't autovivify stash entries. A new method
get_or_add_package_symbol can now be used for that behavior.
Packages Collection.
Manipulating stashes (Perl's symbol tables) is occasionally necessary,
but incredibly messy, and easy to get wrong. The Perl 5 module
Package::Stash hides all of that behind a simple API.