Add ChunkProviderFlat for diff visibility.
Add ChunkProviderGenerate for diff visibility.
Add ChunkProviderHell for diff visibility.
Add ChunkProviderTheEnd for diff visibility.
Add IChunkProvider for diff visibility.
Performance improvements for chunk handling.
This should give a nice performance boost with various chunk operations.
Conflicts:
	src/main/java/net/minecraft/server/ChunkProviderServer.java
	src/main/java/net/minecraft/server/World.java
	src/main/java/net/minecraft/server/WorldServer.java
	src/main/java/org/bukkit/craftbukkit/CraftWorld.java
	src/main/java/org/bukkit/craftbukkit/util/LongHashSet.java