Add new tutorial on quadrotors.

Inspired by the cat and mouse game.
Use the waypoint actuator for the quadrotor.
Merge branch 'master' of ssh://trac.laas.fr/git/robots/morse
[ros] docstring use ros_class variable

Used to create the topic and to generate doc.
While here, add a default_frame_id for some components, the one without
will keep the morse convention, which is the same than the topic name
("/robot/sensor"). Which can also be overriden by an kwargs of name
"frame_id".