+ modify nc_tparm.h, adding guards against repeated inclusion, and
allowing TPARM_ARG to be overridden.
+ fix some strict compiler warnings in ncurses library.
+ add configure script --enable-sp-funcs to enable the new set of
extended functions.
+ start integrating patches by Juergen Pfeifer:
+ add extended functions which specify the SCREEN pointer for several
curses functions which use the global SP (these are incomplete;
some internals work is needed to complete these).
+ add special cases to configure script for MinGW port.
