ncurses 5.6 - patch 20080322

ncurses 5.6 - patch 20080322

+ fill in extended-color pair two more places in wbkgrndset() and
  waddch_nosync() (prompted by Sedeno's patch).
+ fill in extended-color pair in _nc_build_wch() to make colors work
  for wide-characters using extended-colors (patch by Alejandro R
  Sedeno).
+ add x/X toggles to ncurses.c C color test to test/demo
  wide-characters with extended-colors.
+ add a/A toggles to ncurses.c c/C color tests.
+ modify test/ditto.c to use use_screen().
+ finish modifying test/rain.c to demonstrate threads.