Make manager for PBP indexing

[jadball]

More of a note-to-self!

Just ran into this - corrected a dataset for half-scan acquisition, set up the point-by-point object, sent the job to the cluster. Because the cluster job re-imports the dataset and re-generates the icolf, it forgot about the ybincens recalculation.

[jonwright]

I did notice this on the notebook with Loïc - dataset.save() does not save ybins...