ncurses 5.7 - patch 20090906

+ fix typo s/is_timeout/is_notimeout/ which made "man is_notimeout" not
  work.
+ add null-pointer checks to other opaque-functions.
+ add is_pad() and is_subwin() functions for opaque access to WINDOW
  (discussion with Mark Dickinson).
+ correct merge to lib_newterm.c, which broke when sp-funcs was
  enabled.