Stop zombie bash parties

[kevingranade]

Summary

SUMMARY: Bugfixes "Prevent monsters from bashing obstacles based on tracking sounds."

Purpose of change

Zombie bash parties have been a problem for a long time now. One zombie hears a noise and starts wandering toward it.
The zombie encounters something it thinks it can bash through, frequently a car, and starts bashing it.
The noise attracts other zombies, more bashing ensues.

Describe the solution

Zombies simply don't bash when all they're doing is tracking a noise.
They will still bash when they see or saw a player recently and are walking to their last known location.
They will still bash when tracking scent.

Describe alternatives you've considered

I think we should whitelist some "sounds like a living creature" noises and set a flag that re-enables bashing when following that kind of noise.

Testing

Make yourself invisible and scentless, spawn a bunch of zombies and a car.
Throw a rock at the car. The zombies should approach it, but not start smashing it to pieces.

[esotericist]

so in the process of testing this, i discovered that monsters with CAN_OPEN_DOORS will not open doors in order to reach sound sources with this PR.

the apparent cause of this is needing the moved variable to be set true at some point in monster::move(), which doesn't happen when we bail out of the bash evaluation span with the wander check.

monmove.cpp, around line 1024:

[esotericist]

i have no idea if my fix is adequate. i do know it causes ferals to open all doors along their path, like some kind of compulsion:

personally, i kinda like this as a "let's make the path as clear as we can" thing, but it might be weird in some contexts.