Improve calendar nav for in-between days

See merge request !359

Did nothing in this case previously

Release 4.0.0.dev0

See merge request !358

Translations update from Weblate

See merge request !322

Currently translated at 30.7% (12 of 39 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil-Frontend
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil-frontend/uk/

Currently translated at 30.7% (12 of 39 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil-Frontend
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil-frontend/ru/

Currently translated at 100.0% (39 of 39 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil-Frontend
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil-frontend/de/

Translations update from Weblate

See merge request !357

Currently translated at 100.0% (318 of 318 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil/de/

Update .prettierignore

See merge request !353

Resolve "Add simple course book list"

Closes #256 and #63

See merge request !350

Implement infinite scrolling and by date navigation for coursebook

See merge request !355

& do the TODO.
Also leave a pointer how to improve it (even) more.

It does not have to be the currentDate. This holds only for the first day.

Updating the hash fragment causes a small delay while scrolling.
=> Update only after user finished scrolling.
Uses requestIdleCallback
which is not ready for prime time in Safari. But should work elsewhere.