Path following & steering

Some online research turned up this path folowing video tutorial shows (at 7:00) a nice animation of a path following algorithm credited to Craig Reynolds

I ended up using something even cruder than this.

With each GPS location, I simply:
- Calculated the Relative Bearing to the target waypoint
  - If the relative bearing of the target was a little bit off to the right, it would steer a little bit to the left
  - If the relative bearing of the target was a lot off to the right, it would steer harder to the left
- Then multiplied the bearing angle by the STEERING_GAIN (0.6)
- Applied this angle to the steering wheel.
This actually worked OK.