+ modify keyname() to use "^X" form only if meta() has been called, or
if keyname() is called without initializing curses, e.g., via
initscr() or newterm() (prompted by LinuxBase #1604).
+ document some portability issues in man/curs_util.3x
+ add a shadow copy of TTY buffer to _nc_prescreen to fix applications
broken by moving that data into SCREEN (cf: 20061230).