Make polearm brand generation sane (?)

Chance of SPWPN_NORMAL by the time SPWPN_VORPAl was reached was
almost exactly 4/5; (1/5 * 4/5) + (1/5 * 1/5 * 1/6) is roughly
1/6 = 16.6...%, which * 69% (the chance of that brand not being
overriden by a later brand) is roughly 12%.

hooray
also don't leak information about invisible beholders
Small polearm brand correction

Since the odds of getting SPWPN_NORMAL at the SPWPN_VORPAL line
were 3/4ths of what they were for spears, thanks to the SPWPN_
PROTECTION chance...
Fix numeric glyph overrides (#9243)

We had used negative numbers to indicate that the character shouldn't be
mapped through the char_set; but that doesn't work anymore.

In my testing, hex item_glyph overrides seem not to have worked since
0.12 when they were introduced.  mon_glyph was broken more recently.
allow getting only valid actors from mids

normally, we could get the dummy monsters for YOU_FAULTLESS or
ANON_FRIEND
handle monsters enslaving other monsters properly

setting the monster's foe unconditonally to the player is wrong, for
instance in the arena
don't credit enchanted monster kills to the player in the arena
Clean up tentacle mapping arrays further.
Fix tornado cloud names (#9244).
Fix mon_glyph override-by-glyph.

Since 0.16-a0-796-g279ce45, something like mon_glyph += s : B  has
only affected the first monster type with that glyph.  Make it affect
everything as intended.
don't draw the current time in the arena
Expand liches' magical repertoire.

They get spells in a fashion reminiscent of panlords, with spells
from two schools and an escape spell.

The exact spell sets could use adjustment; thus the branch this is
landing on initially.
pick some random spells from the list instead of all of them
simplify
simplify some more
ensure liches always get a reasonable number of spells

also, don't disallow choosing the same spell set twice - nothing wrong
with that now that we don't just pick a fixed number of schools
add a bunch more spell options
no reason to actually use spell type enums here anymore
improve lich spell selection

this moves the split entirely to usefulness rather than school. i'll add
back in some checks to encourage similar-schooled spells later.
simplify