Giving rolling papers to the professions that start with weed.

Cause that's just cruel to give them a bag of grass but no means of
smoking it.
Optional query is optional (soldering)
Fix mon_at cache problems (#2756, #2759).
Fixes missing spawns for some of the caseless weapons.
Fix remove_zombie() for dead zombies.

mon_at() returns -1 if the zombie exists in the map but is dead. This was
causing a dead zombie's z_at entry to persist (and then point at a
different, still-living zombie).
Merge some bugfixes.