ncurses 6.0 - patch 20170506

+ modify tic/infocmp display of numeric values to use hexadecimal when
  they are "close" to a power of two, making the result more readable.
+ improve discussion of portability in curs_mouse.3x
+ change line-length for generated html/manpages to 78 columns from 65.
+ improve discussion of line-drawing characters in curs_add_wch.3x
  (prompted by discussion with Lorinczy Zsigmond).
+ cleanup formatting of hackguide.html and ncurses-intro.html
+ add examples for WACS_D_PLUS and WACS_T_PLUS to test/ncurses.c