Added simple class WebotsTCPClient  to open TCP connection top robot server
and return socket for communication with robot.
Added also TCP transducers (abstract class, plus DiffWheels and LightSensor)
to act on robot's wheels and receive light sensor data
Debugged Transducer TCP classes
Added a test program to simulate a type 2 Braitenberg vehicle. Used to test the
WebotsTCP transducer classes.

Fixed some bugs in the TransducerTCP classes. including a fix to the light sensor that reverses
the output form n to MAX-n (because Webots returns  MAX for no stimulus and 0 for max stimulus)

	modified:   src/RobotSimulator/Transducer.py
	modified:   src/Snippets/Two_dialogs_Gui.py
	new file:   src/Snippets/testWebotsBraitenberg.py