CHECK TABLE should check that foreign key relations are correct

Currently there is no easy way for a user to check if a database is consistent.
One can check individual tables with CHECK TABLE but there is now to check that
all foreign key tables has all the required keys and that the original table has all the rows
expected by the foreign key table.

We should extended CHECK TABLE .. EXTENDED or alternative CHECK TABLE ... REFERENCES to check that all foreign key relations are consistent.

This should preferably be done on the upper, sql, level and not in InnoDB.