Acid blob tile (Bloax)
Hydraform & Irrad icons
Webtiles: Don't do too much with undefined items (|amethyst).

If the new item is undefined, just send base_type and quantity to make
that clear to the client. If the old item was undefined, avoid looking
at it and just send everything.
Revert "Use a constant."

This reverts commit 72cfd3c3af10289ee75862c3e85176c02a028426.
Allow z-casting area spells again (#9050).

Oops...
Fix unided rod spell list (#9048)

Two different symptoms:  1. i<letter> on unknown rods showed the actual spell
list; and  2. if any item_glyph overrides exist (even on unrelated items),
the game would crash when showing a cell with an unidentified rod.
Check for definedness, not validity, in item_prefix etc.

This was making unIDed item_infos never get prefixes, because the subtype
was NUM_FOO and hence invalid.  Definedness is enough to avoid the problem
in #9046.
Don't claim unknown rods have spells.

This made i<letter> display the 'Spells' section even though nothing was
listed there.
Constify a pointer array.
Let conjugate_verb conjugate to both singular and plural.

The latter is close to the identity function, except for "be" -> "are".

Also, use verb conjugation in a few more places.
Simplify veh range boost checks
10 GOTO DIJKSTRA
Remove an unneeded check.

If the pointers had been null, we would have already crashed by this
point.  Presumably this was a typo for !*a && !*b, but that is already
handled by the following if (because '\0' is not a digit).
Add a helper function for duration field population
Fix a typo in a comment
Freeze Cocytus solid

Disallow potion use in Cocytus, roughly inspired by the old days
of item destruction.

Should add a bit of mechanical interest to what's widely
considered one of the weaker Hell branches.
Don't display a misleading message for Undeadhunter on a 0-dam hit.
Conjugate.
Revert "Freeze Cocytus solid"

Turned out there'd been a misunderstanding about the level of
consensus present on this one. Reverted pending further
discussion.