(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..d0e791ece9653de90b6e66d5daad3a4629eaa7b9 100755
--- a/lib/dwc.dart
+++ b/lib/dwc.dart
@@ -72,7 +72,10 @@ Future<CompilerResult> run(List<String> args) {
       .transform((_) => (res = new CompilerResult._(messages, compiler.output)))
       .chain((_) => symlinkPubPackages(res, options))
       .chain((_) => emitFiles(compiler.output, options.clean))
-      .transform((_) => res);
+      .transform((_) {
+        _printMessages(messages, options);

[Jennifer Messerly, 2012/12/06 04:00:08]

Messages should be printed as we emit them, not all at once at the end.

[Siggi Cherem (dart-lang), 2012/12/06 18:46:42]

I don't necessarily agree, but I think I might be missing some details. Let's
chat about it in person.

+        return res;
+      });
   }, printTime: true, useColors: options.useColors);
 }
 
@@ -102,6 +105,16 @@ void _createIfNeeded(Path outdir) {
   }
 }
 
+void _printMessages(Messages messages, CompilerOptions options) {
+  for (var message in messages.messages) {

[Jennifer Messerly, 2012/12/06 04:00:08]

verbose messages are always printed now?

[Siggi Cherem (dart-lang), 2012/12/06 18:46:42]

Fixed. 

+    if (options.jsonFormat) {
+      print(message.toJson());
+    } else {
+      print(message);
+    }
+  }
+}
+
 /**
  * Creates a symlink to the pub packages directory in the output location. The
  * returned future completes when the symlink was created (or immediately if it