Django-spectator

Added

- Allow use of Pillow up to v7.2 (from v6.3)

Changed

- Switch from using django-imagekit specs in `spectator/core/imagegenerators.py` to adding `ImageSpecField`s directly on the `Publication` and `Event` models.
- The `spectator_core/includes/thumbnail_*.html` templates have been updated.
- The old image specs in `imagegenerators.py` are deprecated and should no longer be used. They will be removed in a future release.
- This change means working with models' thumbnails is a little easier. e.g. if django-imagekit's "Optimistic" cache file strategy is used, all of a model's thumbnail sizes will have cached files generated when its thumbnail is added or changed.
- Update Boostrap CSS files from v4.3.1 to v4.4.1
- Make devproject's python dependencies a little laxer

Removed

- Drop support for Django 1.11 and 2.1

- Fix issue where the Mapbox map didn't load when creating a new venue in admin.
- Fix issue where the Mapbox venue map marker moved when zooming out.
- Reduce geocoding API calls from Venue add/change admin page.
- Update devproject's Django version from 3.0.0 to 3.0.2

- Breaking change: The `SPECTATOR_GOOGLE_MAPS_API_KEY` is no longer supported. See the README for the new `SPECTATOR_MAPS` setting that replaces it.
- Add option to use Mapbox for Venue maps and geocoding, instead of Google. See the `SPECTATOR_MAPS` setting.
- Checked that it works with Python 3.8 and Django 3.0.

- If the end reading dates for all publications on a year archive page only have year granularity, don't show the months (which was always "January").
- Add `loading="lazy"` to thumbnail images in lists (only works on Chrome).
- Fix sort order of names that end with parentheses like "Sam Taylor (1)".

- Increase thumbnail JPEG quality from 60 to 80.

- Add two ImageFields for uploading images: `Publication.cover` and `Event.ticket`.
- Now installs [ImageKit](https://django-imagekit.readthedocs.io/en/latest/) (which needs [Pillow](https://python-pillow.org) or [PIL](http://www.pythonware.com/products/pil/) to be installed first).
- Publication cover images are displayed in a publication's detail template, and in lists, but not in the sidebar cards. Also in the Admin.
- Event ticket images are displayed in an event's detail template and in the Admin.
- There are new settings (with defaults) related to these images: `SPECTATOR_THUMBNAIL_DETAIL_SIZE`, `SPECTATOR_THUMBNAIL_LIST_SIZE`, `SPECTATOR_EVENTS_DIR_BASE` and `SPECTATOR_READING_DIR_BASE`. See the README for more details.