+ fix an infinite recursion when adding a legacy-coding 8-bit value
using insch() (report by Clemens Ladisch).
+ free home-terminfo string in del_curterm() (patch by Dan Weber).
+ continue integrating "sp-funcs" by Juergen Pfeifer (incomplete).
+ 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.
