Scattered minor monster tweaks.

 * Remove poisonous bites from two spiders that already have distinct
   non-poisonous offense, jumping and orb. The former gets a slight
   damage boost to the bite to compensate (not that the poison was
   previously seen very often anyway, since 5 damage won't get to
   trigger poison against nearly any ac), the latter gets nothing since
   it takes discord or frenzy to even see them bite.
 * Give Mnoleg more exciting attack verbs, since he is juxtaposed
   with klowns now and they get such exciting attack verbs themselves.
   The only influencing aspect of this is that one attack counts as
   a claw for hydras.
 * Give Dissolution 4 more HD, so his poly isn't sad (for now) and
   so that he has a better chance to actually hit extended evasion
   without needing eyeball paralysis.
 * Block Killer Klowns from polymorph / shapeshifters; they're extremely
   weird to get from such, and the top hd area for the either of those
   already got the highly-dangerous birds without needing klowns too.