Fix and remove some vaults.

This is mainly concerning the Vaults. A lot of random vaults in
mini_monsters.des have been prevented from spawning there and a number of
vaults have been removed from vaults_rooms.des. This isn't comprehensive,
but it removes some of the worst offenders.
Monsters' foe memory use game turns instead of player actions.

Also reduce the initial value to something more reasonable.
Clean up conftest.cc after use.
Mark a function static.
Remove unused marshallEnumVal subsystem.
Remove unused option to ignore write errors for save fragments.
Let alarm traps trigger only once.

After they have done their job they're only an annoyance.
Remove some problematic vaults.

The snail statues give XP for tediously killing a defenseless monster, stop
autoexplore, introduce exclusions, etc.  And a tiresome slog through mud goes
against "take it easy".  The vault has been disabled for quite a while and
no one suggested how to fix it.

People randomly combusting for no explainable reason are no good, either --
altars with a caged sacrifice waiting for a worthy adventurer can be somehow
argued for, this series of vaults not really.  Especially if people who die
there can't live in that branch in the first place.

Two piles of human chunks with wands of disintegration with exactly 0 charges
can't be realistically explained as a "duel", either.  It's too silly a
gimmick -- silliness should at least have some reason.
Purge descs for custom monsters from recently removed vaults.
Fix a compiler warning (unused function in tile builds).
Do not place orc sorcerers on D:6

Still a rough ride now but at least not outright unfair.
Ancient zymes

Relatively low-power abyssal monsters which inflict disease (and possible
str and dex damage) passively when near the player. Also has a mild stat-
draining melee attack.
Make zymes obey sanctuary; make undead immune.

For the latter, I used res_rotting(), as that's what sicken() uses.  This
prevents spam.  Currently, vitalized Zinnites still get spammed.
Add a comment

Opening up beam.cc to double-check the order of zap_info bools is far
too much effort.
Lurking Horror

Stalks you out of view. Then charges you and explodes with torment.
Quite the day spoiler if you ask me.
Don't crash when detonating lurking horrors inside a sanctuary
Move another D:6 orc sorcerer deeper
Fix a zyme message
Make new abyssals more common for testing

Revert/adjust later as appropriate.
Refactor amulet and equipment-checking functions.

Move most of the player_* functions related to amulets, and all of the
player_effect_* functions, into class actor, with some overridden in
class player.  Likewise, move player_equip(), player_equip_ego_type(),
and scan_artefacts() into class player, with pure virtuals in class
actor and corresponding implementations in class monster.  Also remove a
few now-redundant functions.

This commit doesn't actually make any kinds of equipment have an effect
on monsters that didn't already, but it should be much easier to do so
now, since the relevant methods are there now.  Monster gourmand,
conservation, faith don't necessarily make sense, but those methods are
in actor anyway for consistency with the rest.

Fixes #6172.  We now check for innate gourmand (etc.) without reference
to suppression.