gEDA-user: [pcb] ps export changes

[DJ Delorie]

I made a few changes to the postscript exporter.  This is code I've
been using for my home etch.

Changes:

* Draw outline layer on all other copper layers when "draw outline" is
  selected.

* Make drill helpers half the board's minimum drill size, not twice
  PCB's minimum drill size.

* Make alignment marks less obtrusive.

* Include commented out helpers for brass paste stencil etching.