Made *.xml reading work

Dapplo.Config.Test/Languages/language_de-DE.xml

@@ -4,4 +4,7 @@
 		<resource name="TestValue">Abbrechen</resource>
 		<resource name="OnlydeDE">BlubDE</resource>
 	</resources>
+	<resources prefix="Core">
+		<resource name="TestValue2">Another value</resource>
+	</resources>
 </language>

Dapplo.Config/Language/ILanguage.cs

@@ -26,9 +26,12 @@ namespace Dapplo.Config.Language
 {
 	/// <summary>
 	/// The base interface for all language objects.
-	/// It is important to have INotifyPropertyChanged, so language changes are directly shown in the UI.
+	/// My advice is that you extend your inteface with this, and the INotifyPropertyChanged,
+	/// so language changes are directly reflected in the UI.
+	/// 
+	/// This extends IDefaultValue, as this it is very common to start with english hard-coded
 	/// </summary>
-	public interface ILanguage : IDefaultValue, INotifyPropertyChanged
+	public interface ILanguage : IDefaultValue
 	{
 	}
 }

Dapplo.Config/Language/LanguageLoader.cs

@@ -31,7 +31,6 @@
 using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
-using System.Xml;
 using System.Xml.Linq;
 
 namespace Dapplo.Config.Language
@@ -62,7 +61,14 @@ public static LanguageLoader Get(string applicationName) {
 			return LoaderStore[applicationName];
 		}
 
-		public LanguageLoader(string applicationName, string defaultLanguage = "en-US", string filePatern = @"language_([a-zA-Z]+-[a-zA-Z]+)\.(ini|xml)")
+		/// <summary>
+		/// Create a LanguageLoader, this is your container for all the ILanguage implementing interfaces.
+		/// You can supply a default language right away.
+		/// </summary>
+		/// <param name="applicationName"></param>
+		/// <param name="defaultLanguage"></param>
+		/// <param name="filePatern">Pattern for the filename, the ietf group needs to be in there!</param>
+		public LanguageLoader(string applicationName, string defaultLanguage = "en-US", string filePatern = @"language_(?<IETF>[a-zA-Z]+-[a-zA-Z]+)\.(ini|xml)")
 		{
 			CurrentLanguage = defaultLanguage;
 			_filePattern = filePatern;
@@ -71,7 +77,7 @@ public LanguageLoader(string applicationName, string defaultLanguage = "en-US",
 			_availableLanguages = (
 				from filename
 				in _files
-				select Regex.Replace(Path.GetFileName(filename), _filePattern, "$1")).Distinct().ToDictionary(x => x, x => CultureInfo.GetCultureInfo(x).NativeName
+				select Regex.Match(Path.GetFileName(filename), _filePattern).Groups["IETF"].Value).Distinct().ToDictionary(x => x, x => CultureInfo.GetCultureInfo(x).NativeName
 			);
 		}
 
@@ -253,10 +259,10 @@ where file.Contains(CurrentLanguage)
 					newIni = await IniFile.ReadAsync(languageFile, Encoding.UTF8, token).ConfigureAwait(false);
 				} else if (languageFile.EndsWith(".xml")) {
 					newIni =
-						(from resourcesItem in XDocument.Load(languageFile).Descendants("resources")
-						 group resourcesItem by resourcesItem.Attribute("prefix").Value into resourceItem
-						 from resource in resourceItem.Descendants("resource")
-						select resourceItem).ToDictionary(group => group.Key, group => (IDictionary<string,string>)group.ToDictionary(x => x.Attribute("name").Value, x => x.Value));
+						(from resourcesElement in XDocument.Load(languageFile).Root.Elements("resources")
+						 from resourceElement in resourcesElement.Elements("resource")
+						 group resourceElement by resourcesElement.Attribute("prefix").Value into resourceElementGroup
+						 select resourceElementGroup).ToDictionary(group => group.Key, group => (IDictionary<string,string>)group.ToDictionary(x => x.Attribute("name").Value, x => x.Value));
 				} else {
 					throw new NotSupportedException(string.Format("Can't read the file format for {0}", languageFile));
 				}