[RM-6623] Allow two internal velocities in QSO linemodel

Created on 2021-07-19 16:42:19 by Vincent Le Brun. % Done: 0

Some specific emission lines in QSO remain narrow (OII, OIII, identified by the SIM profile) while the other ones are very broad (and with a LOR profile), so each group of lines should have a specific velocity dispersion