[gamma.geocode] make use of new capabilities of pixel_area
[gamma.geocode] make use of new capabilities of pixel_area

the newest can directly create the ratio of ellp. and facet pixel area,
thus making the commands radcal_MLI and ratio obsolete; the old approach
is kept for backwards compatibility reasons and is selected if the
command pixel_area does not take the required arguments

johntruckenbrodt/pyroSAR,johntruckenbrodt/pyroSAR