+20170610
+ + add option "-xp" to picsmap.c, to use init_extended_pair().
+ + make simple performance fixes for picsmap.c
+ + improve aspect ratio of images read from "convert" in picsmap.c
+
+20170603
+ + add option to picsmap to use color-palette files, e.g., for mapping
+ to xterm-256color.
+ + move the data in SCREEN used for the alloc_pair() function to the
+ end, to restore compatibility between ncurses/ncursesw libtinfo
+ (report/patch by Miroslav Lichvar).
+ + add build-time utility "report_offsets" to help show when the various
+ configurations of tinfo library are compatible or not.
+