Patch for issue 3882: stencils with stroke-thickness set to zero (issue 201520044 by address@hidden)

[dak]

https://codereview.appspot.com/201520044/diff/1/scm/output-ps.scm
File scm/output-ps.scm (right):

https://codereview.appspot.com/201520044/diff/1/scm/output-ps.scm#newcode308
scm/output-ps.scm:308: (if (or (not fill?)(> thickness 0)) "gsave stroke
grestore" "")
That sounds like unnecessary effort in some cases.  How about
          (cond ((not fill?) "stroke")
                ((positive? thickness) "gsave stroke grestore fill")
                (else "fill")))

Zero thickness without fill seems a bit awkward.  It's the odd man out
after this change.

https://codereview.appspot.com/201520044/