Now the playback state of a stream is loaded only when needed (i.e. when the stream is visible), just as it is done with thumbnails.
Removed `StateObjectsListAdapter.java`, which used to load the state of every stream at list instantiation, generating slowdowns and freezes.
- add HistoryInfoItem (deriving from StreamInfoItem)
in order to add a special options menu for the list items
- delete HistoryActivity and everything that belongs to its UI (not the
manager tho)
- put everything that is local into local. (subscriptions still missing)