Multiple changes:
* Slight rearrangement of help message.
* Fixed bug where "Dead" flag wasn't being displayed with
--showallflags.
* Added option "-saf" as a shortcut for --showallflags.
* Creature origin (memory pointer) and civilization number are
displayed in the multi-line listing.
* Split logic for testing if creature is to be used off into it's
own function, which is easier to read.
* Added "--type" filter, which can select tame creatures, wild
creatures, demonic creatures, and so on. If the creature type
hasn't been changed from the default of DWARF then's it's
automatically changed to ALL (but can still explicitly be set
via '-c DWARF')
* Added actions to tame selected creatures and to mark them for
butchering.