Adirelle:
	- Use the section listing API in the filter dropdown menu.
	- Do not forget to wipe the reused table in containerProto:IterateSections.
	- The visibility dropdown plugin uses the brand new section iterator.
	- Added section listing and iterating API to the containerFrame class.
	- FilterOverride uses the same format as core for section keys.
	- Moved BuildSectionKey and SplitSectionKey to Utility.lua.
