Fix for C343-17, stuck in pit after xorn poly

* C343-17:   After polymorphing into a xorn and returning to human form, player
             can be stuck in a pit that isn't there.
             Author:  Bulwersator
             Source:  https://github.com/Bulwersator/UnNetHackPlus/commit/f58badbede0dc6ebcf2a0f4218bfdb0f8423acaa
Fix for C343-24, documentation for null option

* C343-24:   Documented default for option "null" is "off"; default is actually
             "on".
             Author:  Bulwersator
             Source:  https://github.com/Bulwersator/UnNetHackPlus/commit/a6d7e394d2f5a624205fd082545650915f2e3ad9
C343-52:  objects destroyed by burning oil

* C343-52:   Worn or wielded objects destroyed by dipping into lit potions of
             oil are not handled properly; this can result in odd game behavior.
             Author:  Patric Mueller
             Source:  http://sourceforge.net/p/unnethack/code/1422/
C343-57:  #enhance command descriptions

* C343-57:   #enhance command descriptions in Guidebook and game do not match.
             Author:  SGrunt (via Bulwersator)
             Source:  https://github.com/Bulwersator/UnNetHackPlus/commit/5e60f1e82d9a26f7c899a01584c6304fcd41ad09
C343-58:  #conduct command description

* C343-58    #conduct command description grammar is poor
             Author:  SGrunt (via Bulwersator)
             Source:  https://github.com/Bulwersator/UnNetHackPlus/commit/2c09c93ade52da17a16fd0cd1304952ceb0f3387
C343-77:  horse forelimb is a hoof, not a claw

* C343-77:   Some messages referring to monsters that look like horses refer
             to claws.
             Author:  SGrunt
             Source:  https://github.com/sgrunt/GruntHack/commit/0333ed27591ecbb57f90e7adc6ae8aecfdbaf7a5