[actuator] Improve light actuator

Provide properties to configure size, distance, light color and energy
Update the doc
[actuator] add a service to toggle the light
[builder] add a set_color method
[builder] Add some argument to environment to disable auto renaming

The default behaviour is still to do magic renaming by default.
Contributed by Felix Meßmer
[builder] Introduce two new basic objects: empty and cordsys

From Felix Meßmer