Fix the event type taking 4 bytes (instead of one) on the network.

It is also the occasion for a little refactoring.
Fix event timestamp being 64 bits (instead of 32).
Fix server not actually broadcasting world state.
Fix confusion between Entities and Characters.
Fix segmentation fault when an entity could not be deserialized.
Fix reading too many bytes when reading the number of entities in a packet.
Add more verbose logging.
Merge pull request #34 from Neki/topic/bf_various_network_fixes