OpenAtlas

This update is mostly about system improvements concerning file structure, logging, tests and similar.
A complete list of changes is available here: 7.9.0.

• Many fixes, general improvements and manual additions

• The file structure has been changed to consolidate project file directories (#1912).
  Be sure to read the upgrade notes (install/upgrade/upgrade.md) and be aware, that external applications/scripts, e.g. backup scripts or presentation sites might need adaptions too.