Current SecureForm implementation generates CSRF secret using
`os.urandom()` every time when application start up. CSRF secret is used
to calculate csrf_token check value, so if someone would use a command
similar to

    gunicorn --workers=8 app

to run his flask-admin app on production then most form submissions
would silently fail (silently - as for now, it is probably another one
bug).

Instead of custom `os.urandom()` logic the `app.secret_key` value should
be used to produce CSRF token values.

Added support for sqla association proxy in model view.

allow user to set  flag "ignore_hidden"

Fix geoa.GeoJSONField

support for WTForms >= 3.0

Updated hybrid property detection to new sqlalchemy API

Modified hybrid property example to make use of the scaffold mechanism to create filters.

support multiple column sort with column_sortable_list

Update actions.js

Fix url generation with localized named filters.

Create function to toggle row checkbox if all checkboxes were toggled manually

Support single table inheritance for inline models (sqla)

Enable support for after_model_ actions in appengine

Support form_args for appengine

This is needed for export function to work

Coremabu

Add scaffold_list_form to allow edit in list view

Convert readthedocs links for their .org -> .io migration for hosted projects