Dont wait for the mantle to load, skip it until it's loaded (async)

src/main/java/com/volmit/iris/util/mantle/Mantle.java

@@ -524,4 +524,8 @@ public class Mantle {
 
         slice.iterateSync((xx, yy, zz, t) -> set(x + xx, y + yy, z + zz, t));
     }
+
+    public boolean isLoaded(Chunk c) {
+        return loadedRegions.containsKey(key(c.getX() >> 5, c.getZ() >> 5));
+    }
 }