Add tox.ini file * Factor out `commands` for most environments using {envname} substitution to build pytest commande. * Positional arguments are passed on to `pytest` (others may also be passed after a `--`). * Set PATH env variable for tests requiring PostgreSQL. * Also added a `doc` target to build the book. Also update .hgignore exclude .tox directory (where virtualenvs will be created and cubicweb.egg-info created by sdist command). Closes #5447161.

Tutorials
~~~~~~~~~

We present a few tutorials of different levels. The blog building
tutorial introduces one smoothly to the basic concepts.

Then there is a photo gallery construction tutorial which highlights
more advanced concepts such as unit tests, security settings,
migration scripts.

.. toctree::
   :maxdepth: 1

   base/index
   advanced/index
   tools/windmill.rst
   textreports/index
   dataimport/index