Logic in ropp_fm_bg2ro_1d.f90 when levels already exist

[Stig Syndergaard]

The logic in ropp_fm_bg2ro_1d.f90 on which levels to forward model to was changed here: https://trac.romsaf.org/ropp/changeset/4906/ropp_src/branches/dev/Share/dmi_trunk_8.1/ropp_fm/tools/ropp_fm_bg2ro_1d.f90

This prevents the use of e.g., -247L if one wants that from a bg file that already has lev2a in it.

Revise if that is the way we want it. Perhaps this would be better:

IF (use_247L) THEN

CALL set_obs_levels_refrac_247(ro_data, obs_refrac, state) ! 247 pre-defined levels

ELSEIF (ro_data%lev2a%Npoints>0) THEN

CALL set_obs_levels_refrac_file(ro_data, obs_refrac) ! levels from file

ELSE

CALL set_obs_levels_refrac_uni(ro_data, obs_refrac, geop_min=geop_min, geop_max=geop_max, n_geop=n_geop) ! Uniformly spaced levels

ENDIF