This filter fails several of the verification tests. I haven't been able
to get anyone to fix it, though.

If you have "nulldev" for dev.attributes, then you can't know when you
want to draw in black versus white. That's bad news, especially when
filling polygons that make background to text. This should be fixed!
In the meantime, filling of polygons will be completely disabled by
putting in nulldev for dev.area. (It had been vecarea.)
When that's fixed, correct setting of the variable "mono" should be done.

- author Glenn Kroeger, I think
- comments by Joe Dellinger
