Replace .qmlproject default editor with the .qml one

Extend logic for mimetype matching in QmlJsEditor: Also
handle sub-mimetypes like x-application-qmlproject, which
extends x-application-qml.

src/plugins/qmlprojectmanager/qmlprojectplugin.h

@@ -52,7 +52,6 @@ public:
     virtual void extensionsInitialized();
 
 private:
-    ProjectFilesFactory *m_projectFilesEditorFactory;
     QmlTaskManager *m_qmlTaskManager;
 };