Fix updating chunk count not clearing on world close

core/src/main/java/com/seibel/distanthorizons/core/api/internal/SharedApi.java

@@ -110,6 +110,8 @@ public class SharedApi
 			ThreadPoolUtil.shutdownThreadPools();
 			DebugRenderer.clearRenderables();
 			MC_RENDER.clearTargetFrameBuffer();
+			// needs to be closed on world shutdown to clear out un-processed chunks
+			UPDATING_CHUNK_POS_SET.clear();
 			
 			// recommend that the garbage collector cleans up any objects from the old world and thread pools
 			System.gc();