Add 'loadstart' and 'loadend' events to some of our exciting layers like WFS, GML, GeoRSS, and Text. tests to back it up. (Closes #808)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@4252 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/GML.js

@@ -81,6 +81,7 @@ OpenLayers.Layer.GML = OpenLayers.Class(OpenLayers.Layer.Vector, {
         // loaded after the GML is paited.
         // See http://trac.openlayers.org/ticket/404
         if(this.visibility && !this.loaded){
+            this.events.triggerEvent("loadstart");
             this.loadGML();
         }
     },
@@ -113,6 +114,7 @@ OpenLayers.Layer.GML = OpenLayers.Class(OpenLayers.Layer.Vector, {
 
         var gml = this.format ? new this.format() : new OpenLayers.Format.GML();
         this.addFeatures(gml.read(doc));
+        this.events.triggerEvent("loadend");
     },
     
     /**
@@ -125,6 +127,7 @@ OpenLayers.Layer.GML = OpenLayers.Class(OpenLayers.Layer.Vector, {
      */
     requestFailure: function(request) {
         alert("Error in loading GML file "+this.url);
+        this.events.triggerEvent("loadend");
     },
 
     CLASS_NAME: "OpenLayers.Layer.GML"