Agnpy

I am creating this version just to test that the new .zenodo.json, generated from the codemeta.json using the OSSR tools is correctly parsed by zenodo.

With this new release:
- an update was realised in the data: the MWL SED of PKS1510-089 in 2015 was not properly converted to erg cm-2 s-1;
- a notebook was added, following the referee report, giving some caveats on suing the thermal SED agnpy computes for the DT.

This is release is made just to test the automatic upload on pip via github actions.
There are no significant differences from 0.1.1.

In this release:
1. the absorption on synchrotron photons was added;
2. a check on the EC on CMB is added with a reference SED produced by jetset;
3. the MWL SED data were standardised to be readable with gammapy's `FluxPoints`.

The package gathers now well-tested functionalities and it's time to make its first minor release.

In this release:

- a function including all the model parameters is introduced for the black body SED computations, such that also their SEDs can be wrapped in a fit;
- the SS disk black body SED is now properly normalised to the total disk luminosity;
- the DT black body SED is now properly normalised to the total DT luminosity;
- added some MWL SED for testing the fit capabilities.

In this release the major features added are:

- an exponential cutoff power-law for the electron spectra;

- the possibility to compute the gamma-gamma opacity for misaligned sources (`viewing angle != 0`) for the following targets: point source behind the jet, BLR and the DT.