Enhancement #1435: pragmas invoked from Tools menu

Pragmas integrity_check, quick_check, foreign_key_check and optimize are
integrated in the Tools menu. The actions open a confirmation dialog
(with Help button that opens the corresponding reference page in
sqlite.org) and, after confirmation, opens a new SQL editor tab and runs
there the pragma, showing the possible results.

Sender in executeQuery is null in this case, so a check is added.

Added accelerator to Tools menu entry, which lacked one.

src/MainWindow.h

@@ -299,6 +299,7 @@ private slots:
     void saveFilterAsView();
     void exportFilteredTable();
     void updateInsertDeleteRecordButton();
+    void runSqlNewTab(const QString& query, const QString& title);
 };
 
 #endif