Adding error parsing as per TODO

[williammlu]

Removing old logic and replacing with most recent version of odrivetool's dump_error()

Example python interactive script runs:

>>> od.get_errors(clear=True)
Axis0:
  axis: no error
  motor: no error
  encoder: no error
  controller: no error
Axis1:
  axis: no error
  motor: no error
  encoder: no error
  controller: no error

>>> od.calibrate(
... )
Vbus 48.33V
Calibrating axis 0...
Calibrating axis 1...
Failed calibration with axis error 0x40, motor error 0x1
False
>>> od.get_errors()
Axis0:
  axis: no error
  motor: no error
  encoder: no error
  controller: no error
Axis1:
  axis: Error(s):
    ERROR_MOTOR_FAILED
  motor: Error(s):
    ERROR_PHASE_RESISTANCE_OUT_OF_RANGE
  encoder: no error
  controller: no error
>>> od.preroll

[neomanic]

Hi William, thanks for this. I'm on leave at the moment so I won't have a chance to look for another week or two. The only issue at the moment is that I'm in the slow process of upgrading from an older firmware (which doesn't support dump_errors()) across our robots, so I can't rely on that function being present just yet.