lootabc and showrace options

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.

dat/opthelp

@@ -17,6 +17,7 @@ IBMgraphics    use IBM extended characters for the dungeon        [FALSE]
 ignintr        ignore interrupt signal, including breaks          [FALSE]
 legacy         print introductory message                         [TRUE]
 lit_corridor   show a dark corridor as lit if in sight            [FALSE]
+lootabc        use a/b/c rather than o/i/b when looting           [FALSE]
 mail           enable the mail daemon                             [TRUE]
 null           allow nulls to be sent to your terminal            [TRUE]
                try turning this option off (forcing NetHack to use its own
@@ -29,6 +30,7 @@ pushweapon     when wielding a new weapon, put your previously
 rawio          allow the use of raw I/O                           [FALSE]
 rest_on_space  count the space bar as a rest character            [FALSE]
 safe_pet       prevent you from (knowingly) attacking your pet(s) [TRUE]
+showrace       show yourself by your race rather than by role     [FALSE]
 silent         don't use your terminal's bell sound               [TRUE]
 sortpack       group similar kinds of objects in inventory        [TRUE]
 sound          enable messages about what your character hears    [TRUE]