Add rough support for generating BDF without FontForge

Add rough support for generating BDF without FontForge

This is extremely silly, but it's actually quite functional and
surprisingly compact.  bedstead.c gains the ability to generate a
PostScript file that emits a BDF file rendering each glyph into an image
and then dumping the image in hex.

I still need to get the font metadata right, which is my main reason for
wanting to get away from FontForge, but that shouldn't be difficult.
And the Makefile needs to be updated to make this work properly.  But
the bitmaps are coming out correctly.