Rohan Dahale

Standardize the multifrequency and multisource data format and model interface

1

For fitting different bands at the same time, we need to define MultiRadioLikelihood and use [skymodel](https://github.com/ptiede/Comrade.jl/blob/f996d2ecfd7a8cc7b7250806227b6e6e6a12ce39/src/distributions/radiolikelihood.jl#L20-L24) and [vlbimodel](https://github.com/ptiede/Comrade.jl/blob/f996d2ecfd7a8cc7b7250806227b6e6e6a12ce39/src/distributions/radiolikelihood.jl#L38-L43) for getting residuals and intensity map. Currently `skymodel` and `vlbimodel` accept only...

Add the ability to fit baseline base instrumental noise terms

1

Currently, Comrade uses a fixed way of defining [Likelihood](https://github.com/ptiede/Comrade.jl/blob/f996d2ecfd7a8cc7b7250806227b6e6e6a12ce39/src/distributions/radiolikelihood.jl#L282-L288 ) based on the data products. Moreover, all the model parameters are inside the model visibilities while the sigma is fixed...