Optimise zonify and add support for filling deep water zones
Fill disconnected areas in swamp layout before stairs are placed

Previously the layout could generate small disconnected areas with a staircase.
Theoretically it was possible to get stuck in two bubbles with no way to access the
rest of the level.

Additionally, deep water teleport closets were being generated around the map borders.
These could randomly trap players able to fly or swim.
#5428 Remove gold pickup spam message in evilmike_quicksilver_bait

Set to a single pile of a decent amount of gold.
#5464 Don't create shafts on Crypt:4
Change Xom inner flame message; imitating Vehumet just doesn't seem right.
Add a Screaming Sword message.
Hush an -Og warning.

It's non-obvious that dims will never be more than 4.  Even if at higher
optimization numbers the compiler notices this, I as a human still failed
to do so after first two readings.
Remove some problematic aura vaults

The Pan vaults are potentially ridiculously lethal, possibly dropping
the player next to a pan lord and multiple greater demons while
disabling access to spells, scrolls, wands and god abilities, which
is unreasonable even by Pan standards.

fun_with_auras has interface problems in console, as well as being
questionable thematically. The "angel + profane servitor" idea might
fit better in an Abyss or Zot-only vault?
Add a note about ][ stairs to syntax.txt (courtesy of HangedMan)
Fix fear not properly interrupting word of recall
Another batch of vaults.

Featured are a new Crypt ending (intended to be roughly as challenging
as the other Crypt encompass endings), four Orc endings (because we're
probably all intimately familiar with the current set), and another
three ministairs minivaults.
Remove a swamp ending.

General consensus is that we already have enough rot/miasma-type endings
(_pestilence and _vile) and that this one doesn't distinguish itself
enough to warrant keeping around.