GSM arguments cannot be passed to Observers #37
Description
The current implementation does not allow to something like python GSMObserver16(include_cmb=True) or change the frequency units or the resolution or any other GSM params.
I think this is useful if the user wants to know how the observable sky looks like with the CMB or if it has other units at hand.
An easy fix would be to have BaseObserver accept a GSM object, rather than a class as currently implemented.
I can make a PR if this is of interest.