core (memory/sqla_mapping): fix some technical debt: a first Alembic revision file is joined to migrate existing databases to new mapping. This patch: - set `nullable=False` in various places - drop legacy `message_types` table, and use `Enum` instead - use naming convention, and get rid of anonymous constraint (this is the main reason why the revision file is so long)

.. _contribuing:

===========
contribuing
===========

This part of the documentation is for people willing to contribute to the development of
Libervia and its ecosystem, it is not needed to read this if you only plan to use the
software.

.. toctree::
   :glob:
   :maxdepth: 2

   testing