AppKit.php: added debug switch

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Foundation.php: added debug switch

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
CoreDataBase.php: removed some older code; changed to mysqli; made reading list of databases and tables work

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Obj-C implementation of class SQL harmonized with php version

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>