* arts-2-1-552

* doc/uguide/concept.tex, uguide/development.tex,
doc/uguide/scattering.tex:

Update docs about test cases.

* tests/: Removed.

git-svn-id: https://www.sat.ltu.se/svn/rt/arts/trunk@8300 aaf1aab0-4228-0410-ad68-8dceda47f409