Move the fucntionality of ActionsHandler into ChatbarCache and ActionsModel.
At this stage there wasn't much left that is was doing and the functionality could easily move.
Move the functionality to cache the contents of a chat bar from the room directly and to a new ChatCache object. This works pretty much the same with a few extra check and balances, this also made it easy to put a test suite around the functionality so I did. The current functionality should be identical to what exists.
This is in prep for threads which will require managing even more caches if we create one per thread.
