* Truely allow mixing Postigs and local layers in a project saved into
PostgreSQL. This comes at a cost: project must be saved using a specific action
that will rewrite all local paths with a :gisdatahome: prefix,
* Allow to configure multiple databases. Each database will have its own menu
entry under the "Guided Editing" menu,
* Improved logging and user feedback,
* Zoom on project extent after loading,
* Load project from PostgreSQL after synchronizing offline project (do not keep
offline project open),
* bugfix: download extent not in correct projection,
* bugfix: remove code that was only Python 3.8 compatible.
