Allow sources to turn off

[jeff-regier]

Currently each source is either a star or a galaxy. We should allow for a third possibility: that a source doesn't contribute any photons to any image. Then we can initialize the model with a different source on each "peak" in each image, without certainty that each corresponds to a different star or galaxy.

Alternatively, we could iteratively add sources, based on the current residual images. But starting with way too many sources and allowing them to turn off is probably simpler.

[rgiordan]

I understand Steve is working on this now.