Modified the light sensor transducer to allow reading raw value from webots,
which are highest for the minimum value of the world's source, and lowest for
the highest value of the world's source. This allows the easy implementation
of Braitenberg-like vehicles with inverse ratio connection between stimulus source
and the rest of the system (what Braitenberg calls a negative connenction,
or 'the more the less').
Also modified the HomeoExperiments class and the QTsimulation class
to use the new light transducer.

 Changes to be committed:
	modified:   src/RobotSimulator/Transducer.py
	modified:   src/Simulator/HomeoExperiments.py
	modified:   src/Simulator/HomeoQtSimulation.py