Improve handling of bundle content


Several improvements to the handling of bundle content:
A list of plugins and themes outside bundles as a central place for items so that you only have to add/update them in one place.
Option to pick plugin/theme from list of items that exist in my other bundles (or in the list suggested above).
Option to reorder content in bundles.
Option to give plugins and themes at title.
Option to add a note to plugins and themes.