Recent changes to wand of probing cause it to map unseen terrain when
zapped into the dark (or while blind) and also to reveal tin contents
if the beam hits such. Extend that to discover secret doors, secret
corridors, and traps whether the spot can be seen or not, and also to
reveal egg contents. Previously, secret corridors were converted into
regular corridors when they couldn't be seen but left as is if their
spot could be seen; now they're found and converted either way.
Issue the kaboom sound effect if zapping a magical trap with wand or
spell of cancellation causes it to go "Kaboom!"
A couple of chunks of code has been moved out of zap_updown() and
bhit() into new routine zap_map().
a31be02350