In addition to 'true', 'yes', 'on' and 'false', 'no', 'off',
accept 1 and 0 for the value of a boolean option. Other numeric
values are rejected rather than treated as non-zero.
Relax the parsing for true, false, yes, no to accept one or more
letters instead of requiring at least three for true and false
and full word for yes and no. Full word is still required for
on and off.
Don't report two errors for the same mistake:
|% NETHACKOPTIONS='legacy:flase' ./nethack
| * Illegal parameter for a boolean.
| * Unknown option 'legacy:flase'.
|2 errors in NETHACKOPTIONS.
is changed to
| * 'legacy:flase' is not valid for a boolean.
|1 error in NETHACKOPTIONS.
e9df383bd6