ref: cf2f89c648d55fd28d29213763f276f523fb22c6
dir: /rc/bin/troff2png/
#!/bin/rc troff -ms $* | aux/tr2post | gs -g1000x1600 -r100 -dNOPAUSE -dQUIET \ '-dGraphicsAlphaBits=4' '-dTextAlphaBits=4' \ '-sOUTPUTFILE=-' '-sDEVICE=plan9' - quit.ps | {crop -c 255 255 255; cat >/dev/null} | topng