Add hands_act()

To simplify some repetitive checks of MISSING_HAND.

Still more redundancy that could be cleaned up, of course...
(particularly in transform.cc; mea culpa!)
Refactor verb conjugation.

Move the body of monster::conj_verb into _conjugate_verb, make the latter
non-static, and call the latter from the former.
Simplify conjugation of multi-word "verbs".
Support a few more verbs.
Split grammar code into a new file.
Use verb conjugation functions in a few places.
Allow reflexives in a few unrand messages.
Don't save pointers to temporary string data.
Try harder to find a push destination when sealing doors.

And assert if we cannot.
Don't let AF_DROWN ignore ddoor (Mr. Lobe)

Some 'drowning'-themed attacks use KILLED_BY_WATER; historically,
this used only for "falling into water and dying instantly", &
ouch() assumed this was what was going on... and since instant
death drowning bypasses death's door, monsters that used AF_DROWN
(water nymphs, drowned souls) and a few other effects were able
to kill players through Death's Door.

Plausibly, those effects should not be using KILLED_BY_WATER at
all, but this should fix the problem for now.
Make wizmode superheal remove Breath
Changelog: Insubstantial -> Awakened

Seems to have been overlooked in the earlier change.
Make sure Natasha keeps her wands through death (minmay).

If it was empty, she was refusing to take it, so it got destroyed
permanently. A bit surprised it wasn't causing unlinked item errors,
but it wasn't too hard to track down anyway.
Simplify.

Without the pickupfn parameter, this will still go through pickup_potion
(with no extra checks because _give_monster_item calls pickup_item with
force == true).
Remove a now-unused parameter.
Remove some now-unused beam callbacks.
Remove a now-unneeded variable and part of a debug message.
Refactor ice melting code
Run util/checkwhite on options_guide.txt
Rename "da_counters" to "daction_counters"