TileMap update performance

Discussion: http://www.html5gamedevs.com/topic/7409-tilemaps-changing/

It should remove the problem of updating stuff in a 100x100 tilemap making the engine recalculate every single update.(390 tiles changed in that map makes it a 100x100x390 loop.
Whould make the recalculate parameter in the setCollision functions unnecessary as well.

Author: TimCabbage

src/tilemap/Tilemap.js

@@ -883,6 +883,28 @@ Phaser.Tilemap.prototype = {
 
     },
 
+    /**
+    * Turn off/on the recalculation of faces for tile or collission updates. 
+    * setPreventRecalculate(true) puts recalculation on hold while
+    * setPreventRecalculate(false) recalculates all the changed layers.
+    *
+    * @method Phaser.Tilemap#setPreventRecalculate
+    * @param {boolean} if true it will put the recalculation on hold.
+    */
+    setPreventRecalculate: function (value) {
+        if((value===true)&&(this.preventingRecalculate===false)){
+            this.preventingRecalculate = true;
+            this.needToRecalculate = {};
+        }
+        if((value===false)&&(this.preventRecalculate===true)){
+            this.preventingRecalculate = false;
+            for(var i in this.needToRecalculate){
+                this.calculateFaces(i);
+            }
+            this.needToRecalculate = false;
+        }
+    }
+
     /**
     * Internal function.
     *
@@ -892,6 +914,11 @@ Phaser.Tilemap.prototype = {
     */
     calculateFaces: function (layer) {
 
+        if(this.preventingRecalculate===true){
+            this.needToRecalculate[layer] = true;
+            return;
+        }
+        
         var above = null;
         var below = null;
         var left = null;