do not ignore style.rotation if set to 0 any more. r=crschmidt (closes #1654)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@7672 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Renderer/SVG.js

@@ -267,7 +267,7 @@ OpenLayers.Renderer.SVG = OpenLayers.Class(OpenLayers.Renderer.Elements, {
                 node.setAttributeNS(null, "r", style.pointRadius);
             }
 
-            if (style.rotation && pos) {
+            if (typeof style.rotation != "undefined" && pos) {
                 var rotation = OpenLayers.String.format(
                     "rotate(${0} ${1} ${2})", [style.rotation, pos.x, pos.y]);
                 node.setAttributeNS(null, "transform", rotation);

lib/OpenLayers/Renderer/VML.js

@@ -253,7 +253,7 @@ OpenLayers.Renderer.VML = OpenLayers.Class(OpenLayers.Renderer.Elements, {
         }
 
         // additional rendering for rotated graphics or symbols
-        if (style.rotation) {
+        if (typeof style.rotation != "undefined") {
             if (style.externalGraphic) {
                 this.graphicRotate(node, xOffset, yOffset);
                 // make the fill fully transparent, because we now have