Fix imagemagick compilation on darwin, because it still includes ghostscript which should not be the case
dzen2: new package

"Dzen is a general purpose messaging, notification and menuing program for X11. It was designed to be fast, tiny and scriptable in any language." -- https://github.com/robm/dzen
linux: Fix hash
Revert "gsl: update from 1.15 to 1.16"

Tests fail on i686: http://savannah.gnu.org/bugs/?40176

This reverts commit 6a69d7e89815599404a7c3f837327fd60da8b899.
Updating nvidia legacy 304 to 304.117
haskell-async: add version 2.0.1.5
haskell-DAV: update to version 0.6
haskell-language-c-quote: update to version 0.7.6
haskell-mainland-pretty: update to version 0.2.7
haskell-scientific: update to version 0.1.0.1
haskell-smallcheck: update to version 1.1.1