SUSAN always reruns

[mwaskom]

SUSAN (FSL's smoothing interface) seems to always rerun, even when none of its inputs have changed. This cascades and forces rerunning of the model.

[satra]

it has to do with the number of digits in the mantissa of floating point inputs. i'm going to look into fixing that for hash check. this will lose some precision, but we will make a note of it in our docs under a hacks section.

[satra]

I think this bug should be fixed now. let me know if this still happens.