[Neuroimaging] Nibabel API change - always read as float

[Brendan Moloney]

> And we always convert data to float in functions that obviously work on
> continous-valued data. But in a masking function, we would have to do
> convert data the opposite way.
> 
> Where it get nasty is: what if the data has undergone a spatial
> transformation? The original integer values are then interpolated to
> intermediate values. What is then the right thing to do?

So it sounds like you might need to handle non-integer masks, even 
without this proposal? At least I don't see how this is an argument 
against the proposal.

-Brendan