(ok 4.5) add lock tables, disable keys options

Would be nice if import and export had lock tables and disable keys option, it would greatly speed up the process for large imports/exports.
When importing large datasets if the table was locked and the keys where disabled, the the time needed to insert many rows would be very short like mysql command line import tool does. the keys would be renenabled after inserts finished and recalculated all at once.