Improved fast mode.

BukkitWorld's fast lighting mode now also does what the old fast mode did.
In addition, both fast lighting mode and the fallback resend all modified chunks when done.
This should prevent display issues.

src/main/java/com/sk89q/worldedit/LocalWorld.java

@@ -326,5 +326,12 @@ public abstract class LocalWorld {
         return 127;
     }
 
+    /**
+     * Does some post-processing. Should be called after using fast mode
+     * 
+     * @param chunks the chunks to fix
+     */
+    public void fixAfterFastMode(Iterable<BlockVector2D> chunks) {}
+
     public void fixLighting(Iterable<BlockVector2D> chunks) {}
 }