The amii_get_ext_cmd menu used the first character of each command
as the item identity (id.a_char) and then linearly searched
extcmdlist for the first command starting with that character.
Many commands share a first letter, so picking #airlevel returned
#adjust, #wipe returned #wear, etc. Store the actual index in
id.a_int and read it back directly.
While in that function, size obufp at BUFSZ (was 100) and replace
the unbounded strcpy from extcmdlist[i].ef_txt with strncpy +
explicit NUL.