Changed how encoding is handled

Previously, to ensure that the XML delaration was being written, a `StringWriter` was used. `StringWriter` _always_ outputs `UTF-16`, however, regardless of what the `XDeclaration` is set to. That's a problem, as Sitemap.org _mandates_ `UTF-8` and e.g. Google will reject a sitemap that uses `UTF-16`. To mitigate this, the `StringWriter` is remoted and, instead, a simple approach is taken: simply declare a standalone `XElement` and serialize it to a string alongside the `XDocument`. (Note: Calling `ToString()` on an `XDocument` won't include the `XDeclaration`, which is why the `StringWriter` had previously been used.)

Author: JeremyCaney

OnTopic.AspNetCore.Mvc/Controllers/SitemapController.cs

@@ -107,16 +107,13 @@ public virtual ActionResult Index() {
       /*------------------------------------------------------------------------------------------------------------------------
       | Establish sitemap
       \-----------------------------------------------------------------------------------------------------------------------*/
-      var sitemap = GenerateSitemap(rootTopic);
-      var sitemapFile = new StringBuilder();
-      using (var writer = new StringWriter(sitemapFile)) {
-        sitemap.Save(writer);
-      }
+      var declaration           = new XDeclaration("1.0", "utf-8", "no");
+      var sitemap               = GenerateSitemap(rootTopic);
 
       /*------------------------------------------------------------------------------------------------------------------------
       | Return the homepage view
       \-----------------------------------------------------------------------------------------------------------------------*/
-      return Content(sitemapFile.ToString(), "text/xml");
+      return Content(declaration.ToString() + sitemap.ToString(), "text/xml");
 
     }
 
@@ -129,7 +126,6 @@ public virtual ActionResult Index() {
     /// <returns>The site's homepage view.</returns>
     public virtual XDocument GenerateSitemap(Topic rootTopic) =>
       new XDocument(
-        new XDeclaration("1.0", "utf-8", String.Empty),
         new XElement(_sitemapNamespace + "urlset",
           from topic in rootTopic?.Children
           select AddTopic(topic)