Fix bug where atan PostScript operator returned values that were not in the correct range.
Fix bug where atan PostScript operator returned values that were not in the correct range.

Ignore-this: 679d36b49180c7668f48ebfa6d6ca31b

darcs-hash:20100606005107-86a4e-3698267dbde50f3d784b88ca755e876eb54f874a.gz

nqv/mupdf,nqv/mupdf,nqv/mupdf,nqv/mupdf,nqv/mupdf,nqv/mupdf