Obsoleted methods in old Casing class and redirects to use StringExtensions. Removes eroneous webforms files not needed in the Umbraco.Web prject

(didn't convert the related UI project ones to have code behinds though... one thing at a time and there's a lot of them to do... over time)

src/Umbraco.Web/Mvc/RenderRouteHandler.cs

@@ -274,7 +274,7 @@ namespace Umbraco.Web.Mvc
 					//the template Alias should always be already saved with a safe name.
                     //if there are hyphens in the name and there is a hijacked route, then the Action will need to be attributed
                     // with the action name attribute.
-                    var templateName = global::umbraco.cms.helpers.Casing.SafeAlias(publishedContentRequest.TemplateAlias.Split('.')[0]);
+				    var templateName = publishedContentRequest.TemplateAlias.Split('.')[0].ToSafeAlias();
 					def.ActionName = templateName;
 				}