From Erik, "add strategic TBD 3.0 comments to remind us to remove the 'url'

var from OpenLayers.Tile's constructor." This has no affects other than to
let people know now that this behavior will change in future versions of 
OpenLayers.  #647.


git-svn-id: http://svn.openlayers.org/trunk/openlayers@3034 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Tile.js

@@ -12,6 +12,9 @@
  * about themselves -- such as the URL that they are related to, and their 
  * size - but do not add themselves to the layer div automatically, for 
  * example.
+ * 
+ * TBD 3.0 - remove reference to url in above paragraph
+ * 
  */
 OpenLayers.Tile = OpenLayers.Class.create();
 OpenLayers.Tile.prototype = {
@@ -22,7 +25,11 @@ OpenLayers.Tile.prototype = {
     /** @type OpenLayers.Layer */
     layer: null,
     
-    /** @type String url of the request */
+    /** TBD 3.0 
+     * @deprecated The base tile class does not need an url. This should be 
+     *              handled in subclasses. Does not belong here.
+     * 
+     * @type String url of the request */
     url:null,
 
     /** @type OpenLayers.Bounds */
@@ -38,7 +45,9 @@ OpenLayers.Tile.prototype = {
     /** @type Boolean */
     drawn: false,
 
-    /**
+    /** TBD 3.0 -- remove 'url' from the list of parameters to the constructor.
+     *             there is no need for the base tile class to have a url.
+     * 
     * @constructor
     *
     * @param {OpenLayers.Layer} layer