Django-comments-xtd

* Fixes issue 80, that requests to change the response when clicking
more than once on a comment confirmation link. Up until now clicking
more than once on a comment confirmation link produced a HTTP 404
response. Since version 2.8.1 the response is the same as for the first
click: the user is redirected to the comment's view in the page.
Thanks to ppershing.
* Fixes issue 152, about loading the `staticfiles` templatetag instead of
`static`. Since Django v3.0 the staticfiles app requires using the
latter. Thanks to JonLevy and mennucc.
* Fixes issue 221, about the get_version function. Now it returns the full
version number <major>.<minor>.<patch>. Thanks to mckinly.
* Fixes issue 229, about failing to process empty honeypot field when
posting comments using the REST API. Thanks to TommasoAmici.

* Fixes issue 106, which is about computing the number of nested comments
for every comment at every level down the tree. The fix consists of
adding a new field called 'nested_count' to the XtdComment model. Its
value represents the number of threaded comments under itself. A new
management command, 'initialize_nested_count', can be used to update the
value of the field, the command is idempotent. Two new migrations have
been added: migration 0007 adds the new field, and migration 0008 calls
the 'initialize_nested_count' command to populate the nested_count new
field with correct values.
* Fixes issue 215 about running the tests with Django 3.1 and Python 3.8.

* Fixes issue 208, about the JavaScript plugin not displaying the like and
dislike buttons and the reply link when django-comments-xtd is setup to
allow posting comments only to registered users (who_can_post: "users").
* Fixes issue 212, about missing i18n JavaScript catalog files for Dutch,
German and Russian.

* Fixes issue 188, about loading a templatetags module not required for
the application.
* Fixes issue 196. When extending django-comments-xtd's comment model, the
receiver function that reviews whether nested comments have to be publish
or unpublish is not called.

* Enhancement, closing issue 155 (and 170), on how to post comments via
the web API. Up until version 2.6.2 posting comments required the fields
timestamp, security_hash and honeypot. As of 2.7.0 there is support to
allow Django REST Framework authentication classes: WriteCommentSerializer
send the signal should_request_be_authorize that enables posting comments.
Read the documentation about the web API.
* Enhancement, closing issue 175 on how to customize django-comments-xts
so that user images displayed in comments come from other sources. A new
setting COMMENTS_XTD_API_GET_USER_AVATAR has been added. The docs have
been extended with a page that explains the use case in depth.
* Fixes issue 171, on wrong permission used to decide whether a user is a
moderator. The right permission is django_comments.can_moderate.
(thanks to Ashwani Gupta, ashwani99).
* Fixes issue 136 on missing <link> element in the templates/base.html
file distributed with the tutorial.tar.gz bundle.

* Adds Dutch translation (thanks to Jean-Paul Ladage, jladage).
* Adds Russian translation (thanks to Михаил Рыбкин, MikerStudio).
* Fixesissue 140, which adds the capacity to allow only registered users
to post comments.
* Fixesissue 149, on wrong SQL boolean literal value used when running
special command populate_xtdcomments to load Postgres database with
xtdcomments.
* Fixesissue 154, on using string formatting compatible with Python
versions prior to 3.6.
* Fixesissue 156, on wrong props name "poll_interval". JavaScript plugin
expects uses "polling_interval" while the api/frontend.py module referred
to itas "poll_interval". (thanks to ashwani99).
* Fixesissue 159, about using the same id for all the checkboxes in the
comment list. When ticking one checkbox in a nested form the checkbox of
the main form was ticked. Now each checkbox has a different id, suffixed
with the content of the `reply_to` field.