Utils/Coreplugin: Clean headers.

Change-Id: I1e0d432127651622d40ff990e1866eac9fac46a0
Reviewed-on: http://codereview.qt.nokia.com/3091
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

src/plugins/coreplugin/messageoutputwindow.h

@@ -34,13 +34,10 @@
 #define MESSAGEOUTPUTWINDOW_H
 
 #include "ioutputpane.h"
-#include "outputwindow.h"
-
-#include <QtGui/QShowEvent>
-#include <QtGui/QResizeEvent>
-#include <QtGui/QTextEdit>
 
 namespace Core {
+class OutputWindow;
+
 namespace Internal {
 
 class MessageOutputWindow : public Core::IOutputPane