For gridded layers where the tile lattice on the server doesn't align with the maxExtent on the client, set the layer tileExtent property. r=ahocevar (closes #3002)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@11002 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Grid.js

@@ -25,6 +25,12 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
      */
     tileSize: null,
     
+    /**
+     * APIProperty: tileExtent
+     * {<OpenLayers.Bounds>}
+     */
+    tileExtent: null,
+    
     /** APIProperty: tileOptions
      *  {Object} optional configuration options for <OpenLayers.Tile> instances
      *  created by this Layer, if supported by the tile class.
@@ -446,7 +452,7 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
      * {OpenLayers.Bounds}
      */
     getMaxExtent: function() {
-        return this.maxExtent;
+        return this.tileExtent || this.maxExtent;
     },
     
     /**