Return delay for driving_function_imp_localwfs()

[hagenw]

driving_function_imp_wfs() and driving_function_imp_nfchoa() now both return their processing delay in seconds as last output parameter. This is missing for driving_function_imp_localwfs(). @fietew: could you add this?

[hagenw]

As far as I see it this is solved, as both driving_function_imp_localwfs_sbl() and driving_function_imp_localwfs_vss() return a delay_offset parameter. @fietew can this be closed?

[fietew]

Yes