Erweiterung der UnitTests und kleinere Fixes

AMWD.Common/Extensions/StringExtensions.cs

@@ -2,6 +2,7 @@
 using System.Globalization;
 using System.Linq;
 using System.Text;
+using System.Text.RegularExpressions;
 
 namespace System
 {
@@ -25,6 +26,9 @@ namespace System
 			if (str.Length % 2 == 1)
 				yield break;
 
+			if (Regex.IsMatch(str, "[^0-9a-fA-F]"))
+				yield break;
+
 			for (int i = 0; i < str.Length; i += 2)
 				yield return Convert.ToByte(str.Substring(i, 2), 16);
 		}