Current Chunk for Entity and Block Entities, counts by entity type

This enables us a fast reference to the entities current chunk instead
of having to look it up by hashmap lookups.

We also store counts by type to further enable other performance optimizations in later patches.

Spigot-Server-Patches/Option-to-disable-BlockPhysicsEvent-for-Redstone.patch

@@ -25,7 +25,7 @@ index 38d664e00..e634c3afd 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
-index 93257a38e..d8d1a4c77 100644
+index 8f0a306cc..74ae80646 100644
 --- a/src/main/java/net/minecraft/server/World.java
 +++ b/src/main/java/net/minecraft/server/World.java
 @@ -0,0 +0,0 @@ public abstract class World implements IBlockAccess {