Allow chaining of multible animations

With this commit it is possible to chain more than one animation together for example:
this.mole.anims.play('digging',true).anims.chain('lifting').anims.chain('looking').anims.chain('lowering');

This commit introduces a property nextAnimsQueue. It holds all additional nextAnim-Keys in the order the chain()-method was called. It is handed over to the nextAnim-Property in the stop()-method.

Author: timogroborsch

src/gameobjects/components/Animation.js

@@ -87,6 +87,15 @@ var Animation = new Class({
          */
         this.nextAnim = null;
 
+        /**
+         * A queue of keys of the next Animations to be loaded into this Animation Controller when the current animation completes.
+         *
+         * @name Phaser.GameObjects.Components.Animation#nextAnimsQueue
+         * @type {Array}
+         * @default []
+         */
+        this.nextAnimsQueue = [];
+
         /**
          * Time scale factor.
          *
@@ -321,7 +330,11 @@ var Animation = new Class({
             key = key.key;
         }
 
-        this.nextAnim = key;
+        if(this.nextAnim === null){
+          this.nextAnim = key;
+        } else {
+          this.nextAnimsQueue.push(key);
+        }
 
         return this.parent;
     },
@@ -850,7 +863,7 @@ var Animation = new Class({
         {
             var key = this.nextAnim;
 
-            this.nextAnim = null;
+            this.nextAnim = this.nextAnimsQueue.length > 0 ? this.nextAnimsQueue.shift() : null;
 
             this.play(key);
         }