TODO list

01) Fix bison warnings on parse.yacc.

02) Add groups of users to the config file.

03) Deal with host aliases (CNAME records) rationally.

04) Nestable command aliases

05) Add uid and gid options to sudo and sudoers file.

06) Redo parsing to be more like op(8) with true command aliases where
    can specify uid, gid(s) and part/all of the environment.

07) Add default options to sudoers file (umask, def uid, def gids, dir, PATH).

08) Add a whatnow-style prompt to visudo.

09) Add a SHELLS reserved word that checks against /etc/shells.
