Moving animation methods out of Util.js.

Animation methods get their own module, giving methods more sensible names:

 * `OpenLayers.Animation.requestFrame` (was `OpenLayers.Util.requestAnimationFrame`)
 * `OpenLayers.Animation.start` (was `OpenLayers.Util.startAnimation`)
 * `OpenLayers.Animation.stop` (was `OpenLayers.Util.stopAnimation`)

lib/OpenLayers/Tween.js

@@ -1,10 +1,10 @@
 /* Copyright (c) 2006-2011 by OpenLayers Contributors (see authors.txt for 
  * full list of contributors). Published under the Clear BSD license.  
  * See http://svn.openlayers.org/trunk/openlayers/license.txt for the
- * full text of the license. */
-
-/**
+ * full text of the license.
+ *
  * @requires OpenLayers/BaseTypes/Class.js
+ * @requires OpenLayers/Animation.js
  */
 
 /**
@@ -53,7 +53,7 @@ OpenLayers.Tween = OpenLayers.Class({
     
     /**
      * Property: animationId
-     * {int} Loop id returned by OpenLayers.Util.startAnimation
+     * {int} Loop id returned by OpenLayers.Animation.start
      */
     animationId: null,
     
@@ -91,12 +91,12 @@ OpenLayers.Tween = OpenLayers.Class({
         this.duration = duration;
         this.callbacks = options.callbacks;
         this.time = 0;
-        OpenLayers.Util.stopAnimation(this.animationId);
+        OpenLayers.Animation.stop(this.animationId);
         this.animationId = null;
         if (this.callbacks && this.callbacks.start) {
             this.callbacks.start.call(this, this.begin);
         }
-        this.animationId = OpenLayers.Util.startAnimation(
+        this.animationId = OpenLayers.Animation.start(
             OpenLayers.Function.bind(this.play, this)
         );
     },
@@ -114,7 +114,7 @@ OpenLayers.Tween = OpenLayers.Class({
         if (this.callbacks && this.callbacks.done) {
             this.callbacks.done.call(this, this.finish);
         }
-        OpenLayers.Util.stopAnimation(this.animationId);
+        OpenLayers.Animation.stop(this.animationId);
         this.animationId = null;
         this.playing = false;
     },