Streamline and optimise Constraints

By looking at the installation scr 02 I recognized no pattern in the settings of fkeys beside combined and not combined fkeys.

I think we could have a closer look at the settings, that are possible and use the opportunity to streamliine and optmise our fkey system.

Possible option MATCH FULL (comnined fkeys)

ON UPDATE CASCADE | RESTRICT | NO ACTION | SET NULL | SET DEFAULT (mixed in scr 02)

ON DELETE CASCADE | RESTRICT | NO ACTION | SET NULL | SET DEFAULT 8mixed in scr)

NOT DEFERRABLE | DEFERRABLE INITIALLY IMMEDIATE | DEFERRABLE INITIALLY DEFERRED | DEFERRABLE (maybe necessary for combined keys)