Small fixes for test workflow, add "getting started" to documentation
Leftover from !60 (merged) (changed from a tutorial to "getting started" with pointers), and a few small fixes to make minimal commands work again:
- the
--input
argument for worker tasks (see !41 (merged)) had the help string as default, so would cause problems if not passed - relative paths did not work correctly for
getATree
(used in interactive mode, and with--onlypost
) - a plotIt configuration was mandatory, while it can in principle be empty (used in a test config now)
- if there is only one era, there is no need to run plotIt twice (for split and combined plots)