getting rid of unnecessary, undocumented 'drawn' property on marker. replacing it with accessor function isDrawn(), and putting an isDrawn() in icon as well. all tests pass r=elemoine (Closes #1759)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@8091 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Marker.js

@@ -129,6 +129,17 @@ OpenLayers.Marker = OpenLayers.Class({
         this.lonlat = this.map.getLonLatFromLayerPx(px);
     },
 
+    /**
+     * APIMethod: isDrawn
+     * 
+     * Returns:
+     * {Boolean} Whether or not the marker is drawn.
+     */
+    isDrawn: function() {
+        var isDrawn = (this.icon && this.icon.isDrawn());
+        return isDrawn;   
+    },
+
     /**
      * Method: onScreen
      *