Added additional sensible defaults to Layer.WMS.DEFAULT_PARAMS, and fixed constructor to only set defaults on param keys that aren't already set (e.g. format). Added tests, which pass.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@112 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/WMS.js

@@ -8,7 +8,9 @@ OpenLayers.Layer.WMS.prototype =
         version: "1.1.1",
         request: "GetMap",
         srs: "EPSG:4326",
-        exceptions: "application/vnd.ogc.se_inimage"
+        styles: "",
+        exceptions: "application/vnd.ogc.se_inimage",
+        format: "image/jpeg"
     },
 
     /**
@@ -18,7 +20,7 @@ OpenLayers.Layer.WMS.prototype =
     */
     initialize: function(name, url, params) {
         OpenLayers.Layer.Grid.prototype.initialize.apply(this, arguments);
-        Object.extend(this.params, this.DEFAULT_PARAMS);
+        OpenLayers.Util.applyDefaults( this.params, this.DEFAULT_PARAMS );
     },    
     
     /**