* arts-2-1-561

* absorption.{cc,h}:

(LineRecord): Add member mquantum_numbers.

(LineRecord::ReadFromArtscat4Stream):

Read quantum numbers into string.

(LineRecord::operator<<):

Do not write quantas from Hitran into ARTSCAT-4. They are incompatible
with our format. Instead, use the quantum numbers that were read
from the original ARTSCAT-4 file (if this LineRecord has them).

git-svn-id: https://www.sat.ltu.se/svn/rt/arts/trunk@8311 aaf1aab0-4228-0410-ad68-8dceda47f409