Escape from the iexamine function after a z-level movement

Fixes #6741

Vertical movement also moves the PC a bit horizontal to make the PC appear adjacent to the elevator controls/the elevator floor. But the iexamine function uses the old coordinates when looking for traps. (player starts at 68,58 in the mine, ends up on 68,60 on z-level 0, and there is a funnel at 68,58 on level 0).

Bonus: The traplocation map was not cleared on a vertical movement, that might have caused #6412.