output parameter table

[ntessore]

It would be nice to save the parameter table that Lensed outputs at the end to disk, especially since the order of the parameter in MultiNest's output may be different when derived parameters are present (cf. #204).

[lirui10590]

When I use image plane priors for the background source positions, it sees that the output parameter of the source position are on the image plane too. I think it would be nice to give the positions on source plane.

[ntessore]

@lirui10590 could you open a new issue for this request? It would be good to discuss it separately from this issue