Provide a “Zero Yaw” feature (for Field-Oriented Drive)

The navX-sensor gyro “yaw” angle will drift over time; the amount of drift depends upon the generation of navX-sensor ("Generation 2" navX2-sensors drift less than "Classic" navX-Sensors) and also how firmly the navX-Sensor is mounted to the chassis. While this yaw drift does not normally impact the robot during a competition match, if using field-oriented drive during extended practice sessions it may be necessary to periodically “zero” the yaw. Drivers should be provided a simple way (e.g., a joystick button) with which to zero the yaw.