Client networking = DONE

Finished client's networking code for Kon Tiki milestone.
- Removed OnCityTransitionDelegate, OnCityTransition and
OnCityTransitionProgress events from NetworkController because they
weren't needed.
- Added CHARACTER_CREATE_CITY, CHARACTER_CREATE_CITY_FAILED,
REQUEST_CITY_TOKEN and CITY_TOKEN to PacketType enum, and added
corresponding handlers (missing handler for
CHARACTER_CREATE_CITY_FAILED).
- Cleaned up and pretty much finished CitryTransitionScreen class.