allow more than two tty characters.
David Greenman pointed out that when a process that had been revoked from
it's controlling tty, the "-" sign was detached from any two-character
names.
This gives us more room to breath with tty names, especially with drivers
that support large numbers of ports.. eg: specialix and digiboard.
This does not actually change the current tty names, it just allows room
for reporting more characters if the drivers use them.
