This method writes an analog value as PWM to the specified port on the robot.
The board has a 8-bit PWM, allowing for 256 discrete levels.
Robot.analogWrite() only works on TKD4, located on the Control Board.
It can't be used at the same time as TK0 through TK7.
*value : 0 to 255
Robot.analogWrite(TKD4, x); //increase brightness of an LED on TK0