Store branches and tagged versions in the same array.
Let package validation checks use enforce instead of assert.
Change order of header elements to fix layout issues.
Little error message improvement.
Implement a persistent event scheduler (will be used for email notifications).
Implement am email notification center for package errors and warnings.

This is currently not used or tested, yet.
Store the commit ID of each version/branch.

This will be used later to recognize actual branch/tag updates (currently all tags are always reread and only the HTTP cache avoids redundancy).