[data] Slightly adjustement for 2.70a

Some boxes seems to move a bit in 2.70a, so lower them from a few
centimeter. Fix laser and camera unit-test for 2.70a
[builder] Generate only useful config in multinode situation

In multinode situation, we do not want to create streams and other stuff
for robot simulated on other node. In some case, the initialisation of
streams and co have some unwanted side effects...

It should fix issue reported by Simon in private mails
[bin/morse.in] Blender 2.70a seems ok for blender
[actuator] Introduce ArUco Marker

The ArUco marker is an AR-Marker that allows to compute the camera pose
from images in the ‘real world’.
The purpose of this actuator is to provide a virtual instance of such a
marker in MORSE. By adding an ArUco marker to a MORSE simulation, you can
subsequently stream/export a (virtual) camera image and eventually use
an AR Marker without a physical camera setup or, i.e, test algorithms or
simulate visual servoring.
[doc] Document the addition of arucomarker
Fixed Morsy collision bounds

Reported by Omar Adair Islas Ramírez
Update collision bounds in the robot template

Follow-up of commit 10f7b41c9cc9
[actuators] add new rotorcraft_velocity actuator
[examples] update quadrotor_dynamic_example
[tools] blend dtm use gdal w/python2

as it's the default bindings distributed for most platforms.
[ci] use blender ppa 2.7 + python3.4

increase xvfb window to avoid llvmpipe segfault
xvfb auto-servernum avoid Xvfb failed to start

http://manpages.ubuntu.com/manpages/precise/man1/xvfb-run.1.html
Added a drop-down box to doc to switch between stable and unstable

Similar to what docs.python.org does to switch between Python releases.
This relies on a fairly stupid {stable <-> latest} URL replacement.

While here, changed the title of documentation to 'The MORSE Simulator Documentation'
[cmake] Mark the project stable if we are in a _STABLE branch
[camera] Fix camera handling for blender version < 2.65

The groupMembers api has changed of name several times so deal with it.
Moreover, this API has been added only in 2.63 so 'deal' with it. In
this case, there is no proper way to handle 'grouped object' so #509
will still be an issue.
[core] Remove test against blender < 2.62

We only support Blender 2.62+, so remove test against previous version.
It should be particularly useful here, as transformation3D is probably
an 'hot path'.
[mw] socket reader must return a boolean

Must handle #544 for socket
[middleware/pocolibs] datastream reader must return a bool

Handle #544 for pocolibs
[middleware] moos actuator datastream handler must return bool

Handle #544 for MOOS
[bin/morse] 2.71 seems to works fine for Morse