To verify whether a variable is among the keys of a dictionary there is actually no need to call the keys() function. A dictionary has a __contains__() member which is called when the “in” keyword is used.

Now that we handle the luminosity and the individual component separately for speed reasons, we must not forget to scale the total luminosity appropriately when redshifting. Otherwise the fluxes in the filters will be overestimated by a factor 1+z.

Now that we do not add an AGN component anymore when the AGN fraction is 0, the wavelength grid may change from one model to the other. To work around this issue we save the IGM component into a dictionary with the key being the size of the grid. This is not completely foolproof as two grids of same length may have different wavelengths, though that is quite unlikely given pcigale's architecture. It should be good enough for now.

This reverts commit c160b8f8.

Make model computations much faster. On a test run we spent 20% of the time just computing the luminosity distance. Now the information is just provided by the redshifting module. If the information is not present we just assume a distance of 10 pc.

If there is no redshift information, we assumed that the redshift is 0. Also correct a bogus test in the redshifting module.

Make pdf_analysis parallel. This required important changes. Functions saving data have been moved to the utils.py file. Workers for the parallel processes have been put in workers.py. To make sure we eliminate models incompatible with the age of the universe now the latter is indicated in sed.info for easy access. Ditto for the redshift.

Change the way redshifts are handled. Now all redshifts are specified in pcigale.ini. To compute the χ², we simply take the models corresponding to the closest χ².

Make the source code more compatible with Python 3. As far as I understand the documentation, this should be harmless for Python 2.

Implementation of one module for the redshifting and one for the IGM
attenuation. For now, the IGM module only implements the Meskin (2006)
attenuation; alternative attenuation law can be added with a parameter
in the module to choose which one to apply.