Update preprocessing "tiling" workflow to reflect new API organization

[danielmwatkins]

The preprocessing workflow notebooks are good places to test out the separation of functions and demonstrate the desired workflow.

[danielmwatkins]

I've selected 9 location/date/size cases to use as reference images in testing. We can gradually replace the large image comparisons with these: the whole set only adds up to about 90 MB, and that's with truecolor, falsecolor, landmasks, and segmentation results for all 9 cases and for both the aqua and terra satellites. Here's what the cases look like: