ncurses 6.0 - patch 20170311

+ modify vt100 rs2 string to reset vt52 mode and scrolling regions
  (report/analysis by Robert King) -TD
+ add vt100+4bsd building block, use that for older terminals rather
  than "vt100" which is now mostly used as a building block for
  terminal emulators -TD
+ correct a few spelling errors in terminfo.src comments -TD
+ add fbterm -TD
+ fix a typo in ncurses.c test_attr legend (patch by Petr Vanek).
+ changed internal colorpair_t to a struct, eliminating an internal
  8-bit limit on colors
+ add ncurses/new_pair.h
+ add ncurses/base/new_pair.c with alloc_pair(), find_pair() and
  free_pair() functions
+ add test/demo_new_pair.c