Bounds: Added extendXY() method

This is a simpler variant of the extend() method, but with less overhead.

lib/OpenLayers/BaseTypes/Bounds.js

@@ -392,6 +392,32 @@ OpenLayers.Bounds = OpenLayers.Class({
         }
     },
 
+    /**
+     * APIMethod: extendXY
+     * Extend the bounds to include the XY coordinate specified.
+     *
+     * Parameters:
+     * x - {number} The X part of the the coordinate.
+     * y - {number} The Y part of the the coordinate.
+     */
+    extendXY:function(x, y) {
+        // clear cached center location
+        this.centerLonLat = null;
+
+        if ((this.left == null) || (x < this.left)) {
+            this.left = x;
+        }
+        if ((this.bottom == null) || (y < this.bottom)) {
+            this.bottom = y;
+        }
+        if ((this.right == null) || (x > this.right)) {
+            this.right = x;
+        }
+        if ((this.top == null) || (y > this.top)) {
+            this.top = y;
+        }
+    },
+
     /**
      * APIMethod: containsLonLat
      * Returns whether the bounds object contains the given <OpenLayers.LonLat>.