[RM-8801] check consistency between z_step and LSF

Created on 2024-04-02 08:35:58 by Vincent Le Brun. % Done: 0

in some cases (especially when using log sampling) if the z_step is too large some lines maybe missed (or produce too large/shallow peaks in PDF). A check should be done (error or warning) to ensure that the z_step is consistent with the LSF