* arts-2-1-551

* src/m_doit.cc, src/methods.cc (doit_i_fieldUpdate1D):

Remove doit_i_field_old from inputs. Instead, use a local variables
that's initialized from doit_i_field.

* src/physics_funcs.cc (invplanck):

Convert assertion for radiance < 0 to runtime_error.

git-svn-id: https://www.sat.ltu.se/svn/rt/arts/trunk@8297 aaf1aab0-4228-0410-ad68-8dceda47f409