NetworkManager-pptp: fix path to pppd and pptp, upgrade
Revert "xen: update to version 4.1.2"

This reverts commit af32fd6ce3ce2ae138c2fc2bc5c6067216f8b828.
xen: Support PCI passthrough.

Previous commit reverted Xen back to 4.0.3 because xend from 4.1.* and newer
hangs for unknown reasons.
The new "xl" toolstack from 4.1.* and unstable works, yet PCI passthrough is not
supported by xl in 4.1.* and is broken in the unstable.

With this patch I was able to passthrough ATI Radeon HD 6950 without 3D
acceleration, though, to both Linux and Windows guests. Which is the best
archived result with Xen PCI passthrough on NixOS after trying out all possible
Xen versions.
Same VGA card works fine if passed through into a guest with KVM (acceleration,
GPGPU, everything works). I should have tried KVM from the start.
Add package enca 1.13 to tools/text
pptp: Fix path to `ip`

routing.c has hardcoded /bin/ip. Use ${iproute2}/sbin/ip instead.
KDE NM 0.9.0.4
zathura: version 0.1.2 with plugins

Expression handles new modular structure of zathura and adds support for djvu,
pdf and ps plugins.
zathura: fix broken links in meta information
chromium: Check sha256 per channel in update.sh.

Until this commit we had a single hash of the whole version response from
omahaproxy. This worked well for not updating unnecessarily but only until one
single channel has a new version available.

Unfortunately the dev version is released quite frequently, so the hash is of no
use at all (we could rather directly fetch everything everytime we execute the
script).

This led to this commit, which adds two methods of caching:

First of all, if a perticular version/channel is already in the previous version
of the sources.nix file, don't download it again.

And the second method is to check if the current sha256 is already downloaded
and reads the corresponding sha256 from the lookup table.

So, this should really help to avoid flooding the download servers and to not
stress impatient users too much.
chromium: Update channels to latest versions.

This removes the now obsolete VHASH line in sources.nix aswell.
Julia: update source revision
nix: Update to latest unstable version
Update coq to 8.4
Merge branch 'master' of https://github.com/NixOS/nixpkgs
Correcting filename.
Fixing configure patch for coq 8.3.
virtualbox: Use Linux's kbuild to build modules.

Don't rely on VirtualBox's in-tree build scripts to set include paths correctly
and use the official way of the Linux kernel to build the modules. That way we
don't need to make ugly symlinks in the kernel tree or heavily patch VirtualBox.
virtualbox: Fix wrong path when recursing modules.

The for loop didn't find $curdir, because it was set _after_ the directory has
been changed. The variable is now called $srcroot and is set before the
installPhase is changing directories.
virtualbox: Set depmod path to /do_not_use_depmod.

The scripts/depmod.sh checks whether the path in $DEPMOD is executable and only
executes it if that's the case. So, by setting DEPMOD to "/do_not_use_depmod"
the destination path doesn't exist _and_ thus isn't executable aswell.
virtualbox: Separate modules build and install.

First of all, modules won't install when there is no "make modules" prior to it,
so we're doing this now with a new function called forEachModule, so we can
avoid duplication as much as possible.

In addition this sets $sourcedir to the current directory of the configurePhase,
so we're able to find the source tree later on, after several chdir()s.