Allow multiple docs to be reoved at once, also react on Delete key.

Reviewed-by: ck

src/plugins/help/docsettingspage.h

@@ -68,6 +68,10 @@ private slots:
     void addDocumentation();
     void removeDocumentation();
 
+private:
+    bool eventFilter(QObject *object, QEvent *event);
+    void removeDocumentation(const QList<QListWidgetItem*> items);
+
 private:
     QHelpEngine *m_helpEngine;
     bool m_registeredDocs;