* arts-2-1-450

* src/m_append.h, src/methods.cc (Append):

Clarify built-in docs and add support for appending Vectors row- or
column-wise to Matrices.

git-svn-id: https://www.sat.ltu.se/svn/rt/arts/trunk@8121 aaf1aab0-4228-0410-ad68-8dceda47f409