themeeditor: Make it compile with current Qt5.

- Replace use of obsolete members with their replacements.
- Fix type issue that requires explicitly creating the right object now.
- Update project file to work with Qt5.

Change-Id: I3af2b1520796e977e58c0a01e165c77c469a23b9

utils/themeeditor/main.cpp

@@ -21,7 +21,7 @@
 
 #include "editorwindow.h"
 
-#include <QtGui/QApplication>
+#include <QApplication>
 
 int main(int argc, char* argv[])
 {