A png file with hatching is added, so it can be used for dark squares
in a monochrome theme. It is installed in a new data directory
.../xboard/themes/textures.
pixmapsdir = $(datadir)/games/xboard/pixmaps/textures
dist_pixmaps_DATA = pixmaps/wood_d.xpm pixmaps/wood_l.xpm pixmaps/cross32.xpm pixmaps/cross48.xpm pixmaps/board32.xpm pixmaps/board48.xpm
+### directory and files for pngs
+
+pngdir = $(datadir)/games/xboard/themes/textures
+dist_png_DATA = png/hatch.png
+
### directory and files for sound files
soundsdir = $(datadir)/games/xboard/sounds