Added automatic language switching option to debugger settings

Additionally, hiding of debugger menu entries was done as most of
them are irrelevant for QML debugging.

src/plugins/debugger/debuggermanager.h

@@ -280,7 +280,6 @@ public slots: // FIXME
     void reloadFullStack();
     void operateByInstructionTriggered();
     void startFailed();
-    void languageChanged(const QString &debuggerLanguage);
 
 private:
     Internal::ModulesHandler *modulesHandler() const;