Convert PostScript to EPS files

Current version

ps2eps requires the following formula to be installed:
ghostscript 9.21_4 Interpreter for PostScript and PDF

Formula history

Nikolaus Wittenstein Add descriptions to all remaining homebrew packages
Xu Cheng ps2eps: add test and fix install
Jack Nagel Remove some unnecessary usage of Dir[]
Adam Vandenberg ps2eps: fix options for gcc