Added NetworkInput class.
Merge branch 'master' into feature/networking
Removed empty line.
Removed need to require middleclass in every file.
Extended main menu.
Added multiplayer menu.
Loading multiplayer menu.
Fixed menu selection screen.
Implemented UDP server and client.
Fixed error().
Removed ping because of crashes.
Made the game itself update again.
Fixed ping and enabled again.
Removed global instance variable.
Added class Updateable and put Server into separate class.
Give the world their network client.
Fixed NetworkInput class.
Implemented some networking. Nothing done yet.

Protocol:
Map:<mapname> to load.
Merge branch 'master' into feature/networking

Conflicts:
	src/World.lua
Fixed some serious changes.