Line Sensor Error Handling

[Kython89]

Investigate the root cause of the line sensor seemingly dying.
Detect a dead line sensor in code.
Ignore the line sensor when dead.

Bonus: Ability to reset the line sensor if it dies.

[Kython89]

https://github.com/wpilibsuite/allwpilib/blob/master/wpilibc/src/main/native/include/frc/Counter.h
The following options on the counter should let us easily detect a missing PWM.

We want to update the period when pulses stop.

 void SetUpdateWhenEmpty(bool enabled);

Max period should be set based off of the PWM frequency. I would recommend a 2x safety factor.

void SetMaxPeriod(double maxPeriod) override;

Once the max period is set and the update when empty is enabled the following should tell us if the sensor is working. If GetStopped returns true then the PWM is no longer being sent from the Teensy.

bool GetStopped() const override;