Update python requirements with

    (cd requirements; rm *.txt; make)

This updates Django from version 2.2.9 to version 3.1.
This updates Wagtail from version 2.7.1 to version 2.10.

The virtual environment can be update to the specified versions with

    pip-sync requirements/dev.txt

Update our library patches to the package versions installed by the
previous commit.

The patches should be applied from the virtual environment directory with

    for f in ../patches/*; do patch -p1 < $f; done

Wagtails permission_required has been moved from wagtail.admin.utils to
wagtail.admin.auth [1]. Use new package name.

[1] https://docs.wagtail.io/en/stable/releases/2.7.html.

Some names in wagtail.api.v2 have changed ([1] vs [2])

Update our source accordingly.

[1] https://docs.wagtail.io/en/v2.0/advanced_topics/api/v2/configuration.html
[2] https://docs.wagtail.io/en/v2.10/advanced_topics/api/v2/configuration.html

Create migrations with

    ./manage.py makemigrations

The SiteMiddlware is obsoleted [1]. Use wagtail_site tag instead.

[1] https://docs.wagtail.io/en/stable/releases/2.9.html

Increase the width of the room field in the Contact model. This was
requested by user.

Create migration with

    ./manage.py makemigrations

Add a filter which greps room patterns in a string and converts them to
a link to our twiki room map.

Replace usage of the room_links tag with the new add_room_links filter.

Remove the now unused tag room_link and the function get_room_link which
is only used by this tag.

For "events", room specifications like "SR 1" are often used. However,
this is not a valid room numer as expected by the twiki map.

Translate "SR [1234]" to correct room numbers for the link target.

Remove invalid setting for the SMTP server.

Note: These lines have already been commented out on our production
server.

Wagtail is changing its search API [1]. There is a documentation PR pending at [2].

Our automplete hack - patch to make Wagtail Snippet Chooser use
.autocomplete() instead of .search() - stopped working after the Wagtail
update for the Contact snippet. Use wagtail.search.index.AutocompleteField
in Contact model to specify, which fields should be indexed for autocompletion.

[1] https://github.com/wagtail/wagtail/issues/4937
[2] https://github.com/wagtail/wagtail/issues/4938