ieLUTInvert second argument

[DavidBrainard]

HJ wrote as part of a previous issue:

"We may want to change the second parameter in ieLUTInvert to number of sampling steps or a vector of sampling positions instead of 'resolution'. Let me know which one is more intuitive or preferable."

A) I agree that number of sampling steps is more intuitive than the current factor argument. But whether this should be changed or not depends on how much other code relies on the current convention -- the arg would have to be changed everywhere it is currently used and that may be in many places.

B) Once we decide on the right argument, we should allow it to be passed to displayGet(d,'inverse table').