#20086: Don't allow - and _ in technical names

Work Item: 20086

Should not break any feature as technical names can't be modified

src/Orchard/Utility/Extensions/StringExtensions.cs

@@ -173,9 +173,7 @@ namespace Orchard.Utility.Extensions {
 
             name = RemoveDiacritics(name);
             name = name.Strip(c => 
-                c != '_' 
-                && c != '-' 
-                && !c.IsLetter()
+                !c.IsLetter()
                 && !Char.IsDigit(c)
                 );