stumpwm: update and refactoring

This commit updates the stumpwm to version 0.9.8. Futhermore, it
refactors the expression quite a lot:

* stumpwm has been moved from lisp modules to window-managers.
* stumpwm has been added to the window managers NixOS knows about, this
  enables the user to add stumpwm as a default window manager in his
  NixOS configuration like with Xmonad or i3.
* the package has been split into stumpwm and stumpwmContrib. This is
  due to the fact that development of stumpwm and its extension modules
  has been split into two repositories. As of today, the release is the
  last one before this split. This split into two packages only reflect
  those upcoming upstream changes already.

It is planned to make the addition of the extension modules voluntarily,
like with Xmonads option "enableContribAndExtras". Furthermore it might
be possible to add an option to compile stumpwm with clisp instead of
sbcl.
stumpwm: removed from lisp-packages.
logstash service improvements

* add logstash-contrib plugins package
* add additional options to the logstash service
Added the grassroots DICOM library.
Added the dlib machine learning library.
Fixed the mirror:// download link for GDCM.
Added Christopher Poole to the list of dlib package maintainers.
fritzing: add version 0.9.0b

- An open source prototyping tool for Arduino-based projects
golang: add golint and gotags
megaglest: new package
arduino-core: bump version from 1.0.2 to 1.0.6

- replace fetchurl with fetchgit because googlecode is unmaintained
- remove unnecessary phases
- change license and maintainers
- tested with a few sketches and inotool

- change description according to "Contributors Guide"

change fetchgit to fetchFromgitHub

Closes #4449
Update vim plugin vimproc, and add patch for ghc-mod vim plugin

Closes #4490
lilypond: updated from 2.16.2 to 2.18.2
Merge pull request #4480 from sepi/lilypond-2.18.2

lilypond: updated from 2.16.2 to 2.18.2
Merge pull request #4458 from offlinehacker/pkgs/gotools

golang: add golint and gotags
haskell-xmobar: update to version 0.22.1
change md5sum to sha256sum for a few packages
haskell-packages.nix: remove if-then-else case distinctions by compiler version

These decisions belong into haskell-defaults.nix.
Merge pull request #4498 from robberer/remove/md5

change md5sum to sha256sum for a few packages
why3: update from 0.83 to 0.85