Use same colour format for dvips and (x)dvipdfmx

There's no need for a conditional here as all of the back-ends other 
than pdfmode understand "gray 0".


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5433 de43f980-851b-0410-b2f7-c40aca1f87e0
Tidy up a few unary minus signs


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5434 de43f980-851b-0410-b2f7-c40aca1f87e0