add vboxsf group (for automatic mounting of shared folders)
xserver: Allow to add extra options to xorg config.

This is especially useful if you want to supply a default XRandR configuration,
where you need multiple "Monitor" sections in order to set properties for
specific CRTCs (if not running in zaphod mode).

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
xserver: Allow to set XRandR multi head layout.

This is currently only a very simple implementation which just recurses a list
of heads that get chained together to the right of the corresponding previous
item of the list.

If I forgot about something in the already existing configuration options,
please let me know or if this commit is useless or a duplicate, feel free to
revert. But by looking at implementation before this commit, I only see zaphod
and/or quirky xinerama-like configuration options.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Revert "xserver: Allow to add extra options ...

This reverts commit 1e741f1572b6793b861e2f9820015475ce339ae0 as it is
unnecessary according to @edolstra, because services.xserver.config from another
module will be merged into the configuration.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Merge pull request #60 from dysinger/virtualbox-guest-additions-vboxsf-group

VirtualBox Guest Additions: add vboxsf group (for automatic mounting of shared folders)
LuksRoot: mitigate DMA key recovery attacks by default.
LuksRoot: add more modules to load by default and let users add more or override the list. Added every module
mentioned by most popular guides, benchmarks and discussions to make things just work.