Flush EditSession on CuboidClipboard paste

- Note that using CuboidClipboard is deprecated, and flushQueue should
heve been called anyway

core/src/main/java/com/sk89q/worldedit/CuboidClipboard.java

@@ -693,6 +693,7 @@ public class CuboidClipboard {
                 }
             }
         }
+        editSession.flushQueue();
     }
 
     /**