The TTY driver now only notifies the IS server about function key event,
but does not tell which keys are pressed. The IS servers queries the TTY
driver to find out about this.
Reduced kernel size by 512KB by moving private buffer into cstart() function.
Replaced assertions with erroneous return values. Removed assertions relating
to isuserp(rp), since all processes should become user processes; system
processes are now treated similar to other processes.
