Remove (not working anyway) multiplayer related stuff.
Start working on different gamemodes.
Remove more multiplayer stuff that I forgotten.
Make preparations for the new gamemode stuff.
First implementation of survival level.

Survival level is a normal level, where player is trying to survive as
long as they can.
TODO:
- Disable the ability for player to shoot.
Enum name change. From, for example, EntityTypeS -> EntityType.
Make EventHandlerAnnotation an inner class of EventHandler. To invoke
it: EventHandler.Annotation
The very same thing here, with PluginMetadataAnnotation.
Merge pull request #3 from Matterross/alpha112

Alpha 1.1.2 - same as 1.1.1, only smaller file size.
Better error handling when a class referenced by a plugin doesn't exist.
Implement a system that would allow for not breaking plugins if I break
something... :D
Fix more compatibility issues.
Optimization during texture stitching.
Code cleanup.
Merge branch 'alpha113'