makes SystemDirectories and SystemFiles public.

moves ResolveUrlsFromTextString to TemplateUtilities class and obsoletes other ones.
Fixes an issue if content cache is stored in codegen folder and not in med trust.
Updates the XmlDocument (IDocumentProperty) to always return a value with parsed {localLink} and resolved Urls and cache them so the parsing only happens once.

src/Umbraco.Core/IO/SystemFiles.cs

@@ -8,7 +8,7 @@ using System.Web;
 
 namespace Umbraco.Core.IO
 {
-    internal class SystemFiles
+    public class SystemFiles
     {
 
         public static string AccessXml
@@ -96,7 +96,7 @@ namespace Umbraco.Core.IO
         {
             get
             {
-                if (ContentCacheXmlIsEphemeral)
+                if (ContentCacheXmlIsEphemeral && SystemUtilities.GetCurrentTrustLevel() == AspNetHostingPermissionLevel.Unrestricted)
                 {
                     return Path.Combine(HttpRuntime.CodegenDir, @"UmbracoData\umbraco.config");
                 }
@@ -104,7 +104,7 @@ namespace Umbraco.Core.IO
             }
         }
 
-        public static bool ContentCacheXmlIsEphemeral
+        internal static bool ContentCacheXmlIsEphemeral
         {
             get
             {