[velodyne] extends LaserSensorWithArc remove Arc
[doc] WIP update ROS navigation tutorial
{rosace -> search_and_rescue}
Renamed almost all components class to get rid of *Class

While here, reorganized the MORSE_DATASTREAM_DICT: it now exposes
components as keys, followed by 'abstraction levels' as sub key (proper
support for abstraction level comes in a subsequent commit), followed
by interfaces (pocolibs, ROS, yarp...).
Introduce 'abstraction levels' for component

This commit introduces a new way to define the semantics of a component in
terms of abstraction levels or 'realism' levels.

By adding 'add_level' statements in a component declaration, one may
create new levels that correspond to a specific subset of exported
data fields and/or a custom component implementation.
[builder] Fix some data entries
[testing] Rename search_and_rescue test for consistency purpose
[test] video camera test in MULTITEXTURE = no shadows