Fix the inconsistent behaviour of QCompleter

The TagWidget behaves now similiar to a QLineEdit.
Pressing Enter/Return will now close the completion widget.

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>

qt-ui/tagwidget.h

@@ -19,6 +19,8 @@ public:
 public slots:
         void reparse();
 	void completionSelected(QString);
+protected:
+	void keyPressEvent(QKeyEvent *e);
 private:
         QCompleter *m_completer;
 };