Casts values to double - Fix for ticket SNAP-1045

[mcvittal]

This change allows the Resampling dialog to now successfully open and resample imagery, casting values to Double.

[marpet]

Thanks for this. But this is only a small part of the complete fix. In the dialog the spinner needs to be changed completely to handle floating point values or maybe replace the spinner at all by a number field. Also, the ResamplingOp needs to be changed to consider the floating point values for the resolution.

[mcvittal]

Ok. I should be able to implement the remainder of the changes needed this week and update this pull request with the new commits when I complete the necessary changes.

[CLAassistant]

All committers have signed the CLA.