Replace "feature_toggle" implementation with an easier-to-understand
boolean option called "lootabc".
Provide "showrace", an option to display the hero by race glyph rather
than by role glyph.
Document the above.
Remove some obsolete Mac options.
Incorporate a slightly cleaned up version of <Someone>'s patch to enable a
"pettype:none" startup option that allows one to start the game without a pet.
