Changes to Rift Regeneration

Moved a little of the regeneration code to BlockRift to reduce duplicate
code. Changed RiftRegenerator to iterate over loaded worlds instead of
all worlds. Removed forced rift generation call in
EventHookContainer.onWorldLoad() - I feel it would have minimal
benefits. Rifts now drop World Thread upon regeneration. Generally
cleaned up the code in FastRiftRegenerator and RiftRegenerator.

src/main/java/StevenDimDoors/mod_pocketDim/EventHookContainer.java

@@ -135,11 +135,6 @@ public class EventHookContainer
     		PocketManager.load();
     	}
     	
-    	if (PocketManager.isLoaded())
-    	{
-    		RiftRegenerator.regenerateRiftsInAllWorlds();
-    	}
-    	
     	if (event.world != null)
     	{
     		this.playMusicForDim(event.world);