[devtools] Make PostgresTestDataBaseHandler multi-use friendly Dont init the pgdb twice on the same datadir - If two test case with the same apphome use a Postgres configuration, the handler is initialised twice, so it has to check if the pgdb directory has already been initialized. - Work with the realpath of the pgdb In some cases, the self.config.apphome will resolve symbolic links, but not always. It can result in an attempt to start twice the pg server for the same directory, in the same test run... resulting in failure. Closes #4875827

Data as objects
===============

In this chapter, we will introduce the objects that are used to handle
the logic associated to the data stored in the database.

.. toctree::
   :maxdepth: 1

   data-as-objects
   load-sort
   adapters
   application-logic