[Dprglist] Assisting PID odometry with an IMU

[markus]

> Thanks for adding in the notion of running the A PID slower than the
> L/R PIDs -- that sounds like good advice. I note that you're running
> your PID loops (A, L/R) a *lot* faster than me, as I've been doing
> everything at 20Hz. Hmm.

I only run them so fast because I can, and because I wanted to go
really really fast - never got to that though because I never got
enough traction with the thin wheels. If I use thicker wheels, like
RC race trucks, I lose a lot in dead reckoning odometry accuracy and
in the end that was more important to me.