Move login username/number parsing into a the C++ code (from login.js) since we

need that internal for SSH and RLogin support of fast-logons.
So, now, even if logging in via SSH or Rlogin, the sys_status SS_FASTLOGON
flag will be set when the user specifies "!username-or-number" during logon and
then the logon.js can use that to determine what to display (or not) to the
user, during logon.

The QWK logon support ("*username-or-number") is also handled in this new
sbbs_t method: parse_login().

This means the fast_logon_char is no longer configurable (hard-coded to '!')
and the modopts.ini options are going to be parsed by logon.js from the [logon]
section (not the [login] section).

You still must set fast_logon=true in the [logon] section of modopts.ini to
enable the fast-logon option for users.