Model 3 driver for class 4 and 5 SmartMotors

[klauer]

The SLAC accelerator has worked a considerable amount with the Animatics SmartMotors, as they are used extensively in the LCLS and now the LCLS-II undulator hall.

There have been many changes in the SLAC accelerator motor fork that brings a number of improvements to the motor record support:

https://github.com/klauer/motor/commits/smartmotor_R6-10

The model 3 driver adds:

• SmartMotor class 4/5 support
• CANbus-based multi-axis support with a virtual axis
• Automatic communication re-sync after a failure
• PID settings, overcurrent/overtemperature monitoring, etc.

I made an attempt to pull those commits out from the accelerator fork to bring the work back to the collaboration, but failed to do that while I still had access to the hardware. As-is, this would likely need some work before a PR could be opened. Feel free to close this issue if not relevant.

cc @alexmontironi

[kmpeters]

If SLAC wants to share a link to the newer version of the SmartMotor support, I'm happy to include it here.

[klauer]

Ping @alexmontironi (the new lead for this effort as I no longer work with SmartMotors; but I'd be happy to help her with this if I can)