Processing multiple target fields in the same measurement set

[KshitijT]

Following discussions with @gigjozsa and @viralp , I think there is a need for the pipeline to be able to process multiple target fields without having to repeat processes like calibrator flagging and 1GC calibration. This might be implemented as:

1. Carry out all processes upto but not including split_data and name the output products by the common prefix. Apply the 1GC tables to all the specified target fields.
2. When splitting, include the target name or some designator in the split dataset (I think we just append the prefix currently).
3. Loop self-calibration and imaging over all the target fields.
4. Save the calibration and imaging products of different fields into separate folders.

This is not a priority; but if we want to do mosaicing at some point, we probably need to do something of this sort?

[bennahugo]

Or do a joint deconvolution with ddfacet. It does require that the model is kept in the intrinsic scale of course though, so can't be done with WSclean

[KshitijT]

This was done by @molnard89 long ago, closing this issue. Mosaicking covered by other issues.