rename fit.workflow(calibration)

[simonpcouch]

I'm wondering if we should adapt the name slightly to make it more obvious that this the data for calibration, rather than, say, the method. data_calibration, calibration_data, calibration_set?

Originally posted by @hfrick in #262 (comment)

I'm on board for this, but don't have much of a preference among them. Let's bring this to the group to be considered along with the "inner split" verbiage.