[0.3.5] Numerous changes; see detailed desc.

+ Add handling to Packet30PlayerUpdate
+ Add updating of players' client addresses/ports upon packet receipt
+ Disconnected players are now removed from the World
[0.3.6] Add Vector3D class for bullet trajectory handling
[0.3.7] Add handling to Packet40WeaponFire

* WeaponType damage dropoff values are now floats