This is used to match the other_arch property of items attempting to be
put into a container. These other_arch values are checked against the
container's "race" string. Example:
* flesh sack -> race -> "hill_giant,beholder"
* "hill giant's head" will match if other_arch is "hill_giant"
* "beholder's tongue" will match if other_arch is "beholder"
It also might be good to match by name instead, but we'll see.
Slaying can now be built from multiple sources. These are:
* weapons, as per before
* player race
* FORCE items, so you can gift slaying to a player
* applied via player changers that contain a player class with a
slaying field
kts of kettek (nyaa)