Starting adding features about sbi_lens

[EiffL]

This is a good decomposition of tasks I think :-) Let's get started:

@dlanzieri can you add the code for the physical model? (point 1)

@Justinezgh can you add the code for generating datasets from this physical model? (point 2)

You can turn each of these bullet points into issues, and assign yourselves to them.

[aboucaud]

Shall we close this issue ?

[dlanzieri]

yes, I guess we can since we completed all the tasks :-)