Documentation and API design revisions: motion & kinematics

I've thoroughly revised the design documents that deal with the motion and
kinematics API:
 <http://www.orocos.org/documentation/deep-shallow-api.html>
 <http://www.orocos.org/documentation/kindyn-doc.html>
 <http://www.orocos.org/documentation/motion-api.html>
The major changes are:
- explicit separation between data flow, execution flow and
  configuration flow.
- (as a result of this) simplification of the motion specification API.
- discussion about the differences between class and component APIs.
                                                                                
As always: comments are very welcome!
                                                                                
Herman

-- 
  K.U.Leuven, Mechanical Eng.,  Mechatronics & Robotics Research Group
    <http://people.mech.kuleuven.ac.be/~bruyninc> Tel: +32 16 322480