Restructure HBA-selfcal

This merge requests aims for condensing and simplifying the new feature of HBA-selfcal in LINC

docs/source/target.rst

@@ -285,6 +285,7 @@ User-defined parameter configuration
 - ``skymodel_fluxlimit``: limits the input skymodel to sources that exceed the given flux density limit in Jy (default: None for **HBA**, i.e. all sources of the catalogue will be kept, and 1.0 for **LBA**)
 - ``selfcal``: perform extensive self-calibration according to the `LiLF`_ scheme (recommended for **LBA** observations) (default: ``false``)
 - ``selfcal_region``: ds9-compatible region file to select the image regions used for the self-calibration
+- ``calib_nchan``: number of channels to be combined when calibration (default: ``0`` (one solution per group) if `selfcal = false`, otherwise `1` (one solution per channel))
 
 A comprehensive explanation of the baseline selection syntax can be found `here`_.