Makefile: switch back to dragon_isp programmer.
serial: silence gcc warnings (unused parameters).
png_to_font: Draw bitpatterns next to arrays.
ht1632c: draw FB with 0-bit on bottom row.
ht1632c: add a 'clear fb' convenience function.
fonts: major rewrite, very ugly.
add 4x5 font
Makefile: -Wextra warnings, dump filesize on link time.
main program: rewriting demo stuff