Further minor iterations for a few early-game monster tiles.
Make Singularities insubstantial
Fix timing for the banishment animation.
Refactor away direct_effect.
Don't enhance Dragon's Call while in Dragon form

It's not an interaction that's especially likely to ever be very relevant.
A demigodlier tile for Frederick.

...since he's been overhauled considerably since the last tile.

Thanks to ontoclasm for helping me tune this up.
Convert AT_{SWOOP,KITE} to AF_{SWOOP,KITE} (MarvinPA).

I can't think of a good way to mention these in describe.cc, and the
monsters that use these already mention the special attacks in their
description, so I'm leaving this out of there for now.
Split knockback from AT_TRAMPLE into a new AF_TRAMPLE.

This makes AT_* purely cosmetic (except AT_REACH_STING, which I have no
idea what to do with in any clean fashion), and allows trample attacks
to possibly have other effects (there could be an AF_KNOCKBACK which
means the monster does not follow along, an AF_COLLIDE which could
combine this with trampling into walls, etc.)
Don't make Vitalization protect enemies (Grunt)
Remove item_mass

Was being used for: fedhas fungal blooms, jelly healing when
eating items, projectile noise, awkward throwing range, and
autotraining of Armour, Dodging, and Stealth. (All based on
body armour mass.)

The former is unchanged (switched to using source monster mass
rather than item mass). Jelly healing now gives a flat +3 hp per
item eaten. Projectile noise uses (projectile damage/3) instead of
(sqrt(item_mass) / 3 + 0.5). Awkward throwing range is now always
to edge of LOS (it essentially was anyway, for anything lighter
than plate & any character stronger than a DEWz). Skill training
uses a linear approximation of the old values.