Implemented multiplayer death and respawning. Several systems were changed to deal with players not necessarily having a character.
Added an EntityBuilder feature to the entity system - this allows the addition of components and setting up of those components to occur before the entity is created, enabling the entity to be in a desired state on creation. The network deserialization code was updated to use this to prevent some race-condition type errors.
Both EntityRef, Prefab and EntityBuilder now inherit a common base ComponentContainer interface.
Removed LocalPlayerComponent - it had a good run but is no longer appropriate. The LocalPlayer helper singleton and ClientComponent's local property replace it.
Merge branch 'multiplayer' of git@github.com:MovingBlocks/Terasology.git into multiplayer

Conflicts:
	src/main/java/org/terasology/logic/characters/CharacterSystem.java
	src/main/java/org/terasology/logic/players/LocalPlayerSystem.java
	src/main/java/org/terasology/logic/players/PlayerInventorySystem.java