(Fix #215) better error printing in editor & extension, adds mapping for editor

lib/dwc.dart

Index: lib/dwc.dart
diff --git a/lib/dwc.dart b/lib/dwc.dart
index dfa89ad87618a2af66f4bcbd83ed5a83dab3e426..a703895eb7b6f785315fb4a96454e7b388c4df99 100755
--- a/lib/dwc.dart
+++ b/lib/dwc.dart
@@ -62,7 +62,7 @@ Future<CompilerResult> run(List<String> args) {
   if (options == null) return new Future.immediate(new CompilerResult());
 
   fileSystem = new ConsoleFileSystem();
-  messages = new Messages(options: options);
+  messages = new Messages(options: options, shouldPrint: true);
 
   return asyncTime('Total time spent on ${options.inputFile}', () {
     var currentDir = new Directory.current().path;