anti-magic trap (trunk only)

Make anti-magic fields do something against targets which have magic
resistance, expanding the functionality of that trap type and giving a
minor drawback to the most valuable intrinsic in the game.  Make them work
against monsters too.

     Heroes who lack magic resistance lose spell energy as before, except
that if they drop below 0 they don't take as hard a hit against max spell
energy as they used to.  Monsters with spell or breath attack and lacking
magic resistance get their ability-last-used field bumped up a little bit,
so they can't cast or breathe for a few turns.  Heroes and monsters who
have magic resistance take HP damage instead.  I retained the concept of
feeling lethargic when being hit by something which normally drains enery,
and also tried to make it be the inverse of a "magical explosion":  the
message refers to torpor/lethargy/sluggishness and cause of death if the
damage happens to be fatal is "anti-magic implosion".  The latter suggests
some sort of compression, so creatures who can pass through walls (xorns
and ghosts) have been given partial resistance and take reduced damage.

doc/fixes35.0

@@ -257,6 +257,7 @@ lembas and cram never rot unless cursed
 multiple squeaks for squeaky boards
 include time, user ID, and play mode in paniclog entries
 add oracle and rumor regarding priestly donations
+anti-magic traps have alternate effect on targets who have magic resistance
 
 
 Platform- and/or Interface-Specific New Features