Add claws-mail and libetpan.

Adds Nix expressions for claws-mail (http://www.claws-mail.org) and a
dependency that is not already in the tree, libetpan
(http://www.etpan.org/libetpan.html).

The Claws expression has flags for toggling the build of various plugins.
proot: remove self.stdenv.lib
Merge remote-tracking branch 'nixos/master' into proot

Conflicts:
	pkgs/tools/system/proot/default.nix
haskell-interpolate: update to version 0.1.0
new package: svg2tikz
pythonPackages.circus: add
python: 3.4.1 -> 3.4.2
new: gist – cli for gist.github.com
Merge branch 'master' of github.com:soenkehahn/nixpkgs

haskell-interpolate: update to version 0.1.0
ujson doesn't build on pypy
Merge pull request #4420 from flazz/master

new: gist – cli for gist.github.com
python-libvirt: update 1.2.7 -> 1.2.9

Should fix breakage due to out-of-sync version with libvirt.
add assertion to keep libvirt and libvirt-python versions in sync
autossh: update from 1.4c to 1.4d
guitarix: update from 0.30.0 to 0.31.0
kde4_next.kdenlive: update from 0.9.8 to 0.9.10
yoshimi: update from 1.2.3 to 1.2.4
Update Monotone-viz source
ccrtp: update from 2.0.6 to 2.0.9
lcms2: update from 2.5 to 2.6