fix https://github.com/icsharpcode/ILSpy/issues/177

NRefactory/ICSharpCode.NRefactory/CSharp/OutputVisitor/OutputVisitor.cs

@@ -963,7 +963,9 @@ namespace ICSharpCode.NRefactory.CSharp
 				case '\v':
 					return "\\v";
 				default:
-					if (char.IsControl(ch) || char.IsSurrogate(ch)) {
+					if (char.IsControl(ch) || char.IsSurrogate(ch) ||
+					    // print all uncommon white spaces as numbers
+					    (char.IsWhiteSpace(ch) && ch != ' ')) {
 						return "\\u" + ((int)ch).ToString("x4");
 					} else {
 						return ch.ToString();