ncurses 5.6 - patch 20070512

ncurses 5.6 - patch 20070512

+ add 'O' (wide-character panel test) in ncurses.c to demonstrate a
  problem reported by Sadrul H Chowdhury with repainting parts of
  a fullwidth cell.
+ modify slk_init() so that if there are preceding calls to
  ripoffline(), those affect the available lines for soft-keys (adapted
  from patch by Clive Nicolson).
+ document some portability issues in man/curs_getyx.3x