AI_MIESAutoPipetteOffset looks odd

[t-b]

While working on using constants for decimal multiplier conversion (#1316) I found https://github.com/AllenInstitute/MIES/blob/3c1d97f1ae6da919552251cc23ab544a2e0b39ca/Packages/MIES/MIES_AmplifierInteraction.ipf#L710-L730.

Some questions:

• If that really supports both IC and VC, the calculation for vdelta is wrong for IC as that the baseline value is in mV in this case and the whole expression gives a current.
• And for VC the vdelta line says pA MOhm / 1000 is milli volts, but that must be more like 1000

The code goes back to 54cf23d4 (Added a MIES function to zero the DC current in Vclamp to use in place of the slow MCC operation auto pipette offset, 2015-08-29).

[t-b]

The current code is correct for VC

•printf "%f\r" 140* 500 / 1000
  70.000000
•printf "%f\r" 140e-12* 500e6 *1000
  70.000000