Fix xpwn on Darwin and other case-insensitive file systems
potrace: allow building on any unix
texlive: add potrace dependency without qualification
fish: Fixed tab completion with sudo (close #2705)

We don't have /sbin and /usr/sbin, so fish complains.
Merge #2692: Use pam_env to properly setup system-wide env
Clojure: bump to 1.6.0.
leiningen: Update to 2.4.0.
gvfs: add more supported protocols in gnome 3.12. Closes #2880
Revert "Merge #2692: Use pam_env to properly setup system-wide env"

This reverts commit 18a0cdd86416a8cbc263cfa8cb96c460a53f7b5c.
Revert "Revert "Merge #2692: Use pam_env to properly setup system-wide env""

This reverts commit 491c088731022463978e595956427e72db6306a9.
filezilla: update from 3.8.0 to 3.8.1, potentially fixes CVE-2013-4668
vimb: Upgrade from 2.2 to 2.4
python-ldap-2.4.15
pgadmin: bump to 1.18.1
davmail: update to 4.5.0
nix-prefetch-scripts: new expression
Merge pull request #2887 from bennofs/nix-prefetch-scripts

nix-prefetch-scripts: new expression
ghc-head: update to version 7.9.20140608
haskell-defaults.nix: ghc-HEAD requires latest mtl
haskell-syb: update to version 0.4.2