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/gui/editorwindow.cpp

@@ -874,7 +874,7 @@ void EditorWindow::createFile(QString filename, QString contents)
     QFile fout(filename);
     fout.open(QFile::WriteOnly);
 
-    fout.write(contents.toAscii());
+    fout.write(contents.toLatin1());
 
     fout.close();
 }