[CF-Devel] Immolation effect added

[Peter Mardahl]

Immolation is disease-like effect you may have seen "dnh"
describing on this list.  An object you hit has a chance
of catching on fire.

Basically, I've modified the disease code to be a bit
more general.

Immolation:
  A player may both "carry" and be "immune" to an
immolation "disease".

When a player who "carries" the immolation disease
hits something physically, he has a chance of passing that
disease to the thing he hit.

That thing will then catch fire.  Nothing is immune to
immolation.  However, some things won't mind being immolated:
any fire-immune creature shall take no damage at all.

How to use immolation:

Place the "immolation" and "immolation_immunity" objects
in a player.  The player will then carry immolation but
will not actually be immolated.

Kills by means of immolation will go to the player's
Wis experience area.

the "wc" field of immolation sets the chance of passing it on during
any given hit:  chance = wc/127.

Right now, "wc" is set to 3, and immolation will kill a 
non-regenerating monster with no protection from fire about
1/10 the time.

Also, immolation will NOT be passed onto anything else the
monster may hit right now.  To enable that, set "armour 0"
in the immolation archetype or object.

Additionally, I have made
creeping_frost
creeping_frost_immunity

which are identical almost to immolation except use cold attacktype
and a bit less fatal.

PeterM