Adds camlp4

Camlp4 is a software system for writing extensible parsers for
programming languages.

Camlp4 was part of the official OCaml distribution until its version
4.01.0.

Homepage: https://github.com/ocaml/camlp4
thunderbird: update from 31.1.0 to 31.1.1
nixUnstable: Update to 1.8pre3823_53b044c
k3d: 0.8.0.2 -> 0.8.03
Add package: snapper

Snapper is a tool for Linux filesystem snapshot management, developed for OpenSuSE.
e2fsprogs: Update to 1.42.12
less: Update to 468
wdiff: Update to 1.2.2
sysstat: Update to 11.0.1 and install systemd units
Bring back Boost 1.55 for now
mercurial: Update to 3.1.1
iproute2: Update to 3.16.0
Add python package: snapper-gui

Graphical frontend for snapper.
Not tested, yet.
Added luaPackages, moved lua sockets and lua filesystem to luaPackages, fixed mudlet deps
Simplified lua-packages function arguments to look nicer in all-packages
Switched from import to callPackage
Refactored to use callPackage right
Added description to languages-support.xml
Assertion throws err message on fail in buildLuaPackage
further improvements to buildLuaPackage