Fixed #22912 -- Warned about a common mistake in tutorial 5.
Fixed #22917 -- Fixed typo in AlterIndexTogether.describe().
Fixed #16184 -- Fixed multiple PostGIS types introspection

Thanks radim.blazek@gmail.com for the report and initial patch.
Testing is tricky, as the failure condition is a bit of an edge
case. inspectapp.InspectDbTests should at least guarantee non
regression.
Fixed a flake8 warning
Add missing spaces to implicitly joined strings
Added spaces to message from 4c39c270af91ddbc213e077fc06b4bf67c7c6e99.
Fixed problem with refs #10811.

When 'to_field' is specified with a FK, then we need to check the pk value
the object.
Fixed #21755 -- Added FK support for REQUIRED_FIELDS.
Added similar behaviour for interactive=True.
Fixed test failures in python 3.x