Fixed logic bug which made it possible for client to stop sending camera updates in IM mode.
Do not run the IM client timer unnecessarily if server doesn't expect camera updates.
Changed the IM filter to use a const reference for the parameters struct.
Marked a SyncManager bug where nonrelevant attribute updates will simply be forgotten.
Marked a Client bug that waiting 2000 ms for the initial IM camera update might not be enough, if the purpose is to wait for user avatar entity creation. Instead there should be a way to mark per-user, that an entity is always relevant.