Fix room state corruption
Fixes corrupting the room state when multiple events of the same type are overwritten with out-of-date state events.
Circles specific:
- Fixes circles-ios#92 (closed)
- Fixes circles-ios#101 (closed)
- Fixes group member counter showing inaccurate count
- Fixes group name on app restart changing to its first name used on creation (and not the current name if it was changed since creation)