These functions are defined in `crs.c' using the curses
library. Unless otherwise noted these routines return #t for
successful completion and #f for failure.
endwin before exiting or escaping from
curses mode temporarily, to do a system call, for example. This routine
will restore termio modes, move the cursor to the lower left corner of
the screen and reset the terminal into the proper non-visual mode. To
resume after a temporary escape, call refresh.