libpar2: Update to 0.4
nzbget: Update to 13.0
Merge pull request #3507 from jochu/nix-update-nzbget

Update nzbget (13.0) and libpar2 (0.4)
gnuplot: Reduce dependency bloat a bit
nixos/znc: add option to add module packages to znc

Besides that add option for extra znc config and fix a lot of stuff
GHC 7.6.x requires older attoparsec to build with aeson 0.7.x.