Merge pull request #141 from LSSTDESC/v3.0.2

Spectractor v3.0.2

• faster matrix multiplications using sparse matrices
• faster PSF computations with numba optimization
• faster Jacobian computations with analytical derivatives
• faster wavelength calibration
• separate fitted parameters from the big FitWorkspace class to manipulate them independently and have specific functions to load and save them in JSON format
• refactor simulation functions to simplify their maintenance (remove unused old functions)
• use Spectrum object as mandatory argument of SpectrumFitworkspace and SpectrogramFitworkspace instead of filename to adapt to Rubin LSST butler usage
• use the new FitParameters class as a parameter class for mathematical models like PSF and ChromaticPSF
• Implement a third diffraction order extraction
• !! DEBUG !! debug wavelength array computation with ADR
• new load/save functions that store/reload the config parameters with a supplementary FITS header in the Spectrum output.
  Short keys must be used because HIERARCH and CONTINUE are incompatible in current FITS headers.
• Fit multiple spectra at the same time with one common atmospheric model to get telescope throughputs
• add timeout errors in case of bad data quality or lousy initialisation of the fit
• replace mirror diameter parameters by effective surface parameter
• increase PWV upper bound