masked (marked bad) scan information does not properly carry through to subplots

[nathanielsherry]

Because the dimensions of the data change, the index values used to store the bad scans are no longer accurate, and now mark the wrong scan as bad, or cause index out of bounds exceptions

for that reason, 'bad scan' data is intentionally discarded in Peakaboo 3 when creating a subplot view

This could be addressed by recalculating the index values, or by storing the 'bad scan' data as a boolean list in the DataSource object so that CopiedDataSource could do the index adjustments for it, as well