[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
[builder] Remove unused helper code
[builder] Remove deprecated method configure_{...}
[builder] Add logic to make component exportable or not

Some component are not logically exportable (such as keyboard or
joystick). Use the flag and associated logic to deal with them.

Fix #490
[blenderapi] Fix key binding for key B

Keyboard key B was mapped to A.
[ros] Do not overwrite topic_suffix if present

Should fix #546
[tools] terrain various fixes

Thanks to Charles L. for the feedback.

- add strength option
- colorspace_settings new in 2.64
- grid `radius` is new in 2.68, was `size` in 2.67a:

http://www.blender.org/documentation/blender_python_api_2_67a_release/bpy.ops.mesh.html#bpy.ops.mesh.primitive_grid_add

http://www.blender.org/documentation/blender_python_api_2_68_release/bpy.ops.mesh.html#bpy.ops.mesh.primitive_grid_add
[template] Fix e03d9b5 by calling the right parent __init__
[doc] Document that the Environment must be created at the end

Fix #548
[modifiers] add missing logger
[modifier] Rework odometry_noise to work at the different odometry level

Fix #553