Inline a function.
Staticalize and simplify.
Remove a test case for old-style portal vaults.
Move maps used by the test suite to dat/des/test

This means there's no dynamic loading of maps anymore.

Also, delete unused regression tests for the long gone old LOS code.
We had copies of both the old and current version.
Avoid an MSVC crash on dry fountains etc (xFleury)

map_cell has a bit field "dungeon_feature_type _feat:8", which MSVC
makes signed.  However, some dungeon_feature_type enumerators are
greater than 127 (beginning with DNGN_DRY_FOUNTAIN = 128).  That results
in some bounds errors when encountering one of those features.

According to the C++ standard, 8 bits should be large enough to hold the
enum (§7.2 [dcl.enum] paragraph 7), so the values in the bit field
should compare equal to the corresponding enumerators (§9.6 [class.bit]
paragraph 4). So it sounds like MSVC is in the wrong. Still, work around
it by casting to uint8_t and then to the full enum type.

At this point maybe we should just use a uint8_t instead of a bit field
(since we have to cast anyway).  However, that doesn't look as nice in gdb...
Fix Jiyva off-by-one error on Slime:$

Previously used 161 despite d703f4dc02d0d08642f20f5d14f471127b4255df.
piety_rank should be a bit more stable than numeric piety values.
Use vector.empty() for emptiness tests.

Unlike some other containers, it's unlikely it's faster than checking size()
anywhere, but let's be consistent.
Greatly reduce the price of Tomes of Destruction.

The value is what dpeg suggested two years ago, might be too low, but it
sadly represents the vault of tomes quite well.  It might be good to make
them worth using instead...
Fix scythe of curses

Check to see if the monster died before checking to see if it has/had
lifeforce to prevent assert crash.
Assert that no cloud is inside a wall.

This makes the abyss crash nearly instantly...  Before, apparently only
ghostly flame had immediately harmful effects (an infinite loop).
Clear invalid clouds when loading a save.
Clear clouds when the abyss morphs a wall.
Skip abyssal clouds when placing a rock worm or a malestorm.
Shave some words off a few datatypes.

(I wonder if this saves even one kilobyte?)
Add more cloud assertions.
Don't place steam under mangroves.

They are somehow "solid", unlike regular trees.
Don't make a cloud when a summoned rock worm poofs.
A yet another mangrove+cloud fix: tornado.
Don't place a cloud covering the malign gateway itself, just next to it.
Don't blow clouds into mangroves, either.  Simplify.