Can't push boulders through iron bars; traps can't roll such through either;
likewise for objects thrown by monsters.
Thrown objects susceptible to breaking might do so when they hit iron bars.
Assorted monsters can pass through iron bars; ditto for polymorphed character.
Attempting to dig iron bars will wake nearby monsters instead of yielding
"you swing your pick-axe through thin air".
Autodig won't accept iron bars as candidate location.
If you stepped on an unknown rolling boulder trap, and that rolling boulder
hit a monster and killed it, you would be called a killer. This makes
playing a pacifism conduct game rather difficult.
- track boulders from unknown rolling boulder traps, and don't charge/credit
hero if they kill monsters. This is done by temporarily setting otrapped on
such boulders.
- boulders from known traps are still charged/credited to the hero
- fix a couple places in ohitmon where is_poisonable wasn't checked along
with opoisoned.
Make pushing a boulder onto a landmine share code with the trap case,
resulting in pits, waking sleepers, et al.
Don't leave a boulder suspended over the new pit, fill it.
Make sure any remaining boulder is placed on top of the pile.
If player sets off landmine, monsters killed are credited to/blamed on player.
