Improvements to GyroTurn

[StephenWelch]

GyroTurn doesn't perform as well as it could. We should add feedforwards - a minimum power to apply to the motors - to overcome static friction inside our gearboxes. This should help eliminate the "creeping" motion where the robot would get within ~35-45 degrees of it's angle target then slow down considerably.

• Feedforward can be calculated by converting from voltage to percent of total output.
• On the practice drivetrain, this voltage is ~0.8V