Switching language redirects to calendar of current week

One-sentence description

Because the calendar date is set by using an anchor (#), switching the language redirects to the events page without the date.

Current behaviour / Reproducing the bug

1. Go to the calendar.
2. Observe the calendar is on the current week.
3. Go to a specific week.
4. Switch language.
5. Redirect to current week (this may redirect to the homepage if #806 (closed) is not fixed yet).

Expected behaviour

When switching the language, the calendar does not reset to the current week.