Allow multiple Broadenings of the same type

[ivh]

currently one one broadening block per transition for each type (instrumental, natural, doppler, pressure) can be handled by the generator. they should be repeatable.

VALD has 2x pressure (vanDerWaals & Stark), for example.

[Griatch]

Made some intial tries with this, optionally looking for a loop iterable RadTransBroadeningNatural.Broadenings with a loop variable "Broadening" ... relatively consistent with previous implementations, but needs more discussion.

[ivh]

We defer this until the next standards are released which hopefully makes this obsolete.