Timetagger

* Improvements to authentication system. It is now friendlier (no more logout each week) and more secure (can revoke access).
* Refactoring of the API server code -> it's now fully async, and the API is public.
* We now have developer docs! (for the library and for the web api).
* Improved menu in the app.

* Fix DST winter-summer transition on Safari iOS.
* Fix `run.py` example for certain python versions.
* Prevent consuming browser shortcuts (no Ctlr/Alt/Meta).

This release implements a new design that [Sophie](https://www.soof.design/) has worked on in the past weeks.

* Move account page to root.

* Changes to how the app is hosted (63):
* Refactor so that the whole app runs at `app/`.
* Timetagger now does not have to be hosted at the root path.
* Implement service worker, so that the app can be used offline.
* Make the app easy to install.
* Autodetect when new version is available, and notify user.
* Fix that using zoom buttons did not zoom to whole weeks/months (65) .
* Tweaks (e.g. duration text).

* Snapping in the timeline occurs in smaller steps (and avoids multiples).
* The two representations of a record (in the timeline and the description) are merged into a single "object".
* Colors are assigned to tag combinations, which is shown on the records, in the overview, and in the stats when in week/month view.
* These colors can be manually assigned too.