Started to implement referee comments

[cosimoNigro]

In this PR I address two comments received from the referee:

• the referee argued that re-implementing the same formulas of Finke 2016 does not constitute validation, but that only comparisons against other software does constitute real validation. Thanks to Andrea we were finally able to perform more crosschecks against jetset, for all the EC cases. Now all the radiative processes plots in the validation section have a comparison with jetset. The jetset SEDs, whose computation is now embedded in the scripts, are obtained with the current developer version of Jetset, will ask Andrea to make a release before the paper is published;

• with the objective of shortening the manuscript I have removed Figure 3 (the EC on DT example). I removed the snippet from the paper and the corresponding script in this repository. I sacrificed this example as it is clearly available in the docs;

• I did some modifications to the Dockerfile.

[jsitarek]

Hi @cosimoNigro,

despite that you already merged it, let me make a few small comments here:

• it would be good that all the curves have the same range, in some of the plots jetset seem to cut off at the lowest energies.
• in same cases the difference are way too large for confort, reaching a factor 2, it would be good to understand if they come from different assumptions. Otherwise, a possibility is that they are affected by the numerical integration uncertainties, do you have a possibility in jetset to apply a finer integration to see if the results do not change considerably? In particular the EC on BLR for r >> Rline difference might be related to the accuracy of integration over angles, those are really tricky cases
• about the difference with CMB, do you know if jetset is using also delta approximation, or full BB spectrum?

[cosimoNigro]

Thanks for the comments Julian, I added them to the relevant issues we were using to discuss the jetset / agnpy comparisons.