This allows us to render entities of any type in timelines, not only entities that have `date`/`startDate`/`endDate` properties

This might be a very good idea and a step towards eliminating Redux in our app in most cases where it's not really required (i.e. most CRUD operations.) Or it's a very dumb idea (if we keep using Redux and now have inconsistent state management.)

The item background is now a shade of the item color

New entitysets do not have a layout by default.

The loading spinner is implemented using CSS transitions, animating the rotate transform of a rectangle. Depending on the rotation angle, the rectangle will create an overflow and scrollbars will be displayed shortly, then disappear again.

* Allows users to focus prev/next list items using arrow keys
* Focuses list items on click
* Selects focused list item by pressing space/enter

…aved

This copies the property values that are present in the old and the new schema.

…22-01`

`TimelineItem` encapsulates logic commonly required when displaying entities in a timeline, e.g. determining which color to use or what the earliest and latest date the entity covers are. This is in preparation for a new chart view, to ensure common display logic can be shared with the existing list view.

This allows sharing the logic across list and chart renderers.

This isn't enabled/visible to users at the moment.

* Supports displaying timeline items in a Gantt-chart like view.
* Supports single-day and multi-day items.
* Supports different degrees of precision (e.g. `2022`, `2022-01`, `2022-01-15`).
* Right now, there's no way to change the scale/resolution of the chart (day/week/month/quarter/year view).

I've added a new dependency, `date-fns`, to work with date intervals. We already use a date utility library (Moment.js), however, the project authors recommend not using Moment.js for new projects and Moment.js doesn't have out-of-the-box support for what I needed (e.g. calculating all the months, quarters, etc. within an interval). `date-fns` is a very modular library and allows us to use only what we need, so this adds less than 1kB to the bundle size.

… so they stay visible even if the timeline item is wider than the viewport

This makes the component code less complex and allows us to reuse logic in the future.

Initially, I kept types a little more relaxed, allowing component consumers to omit certain event handlers. This is handy especially in tests. For example, a test case may not be dependent on passing a real `onChange` handler to a component. When rendering the component in that test, it's convenient to simply omit the `onChange` property rather than passing a no-op event handler.

However, this requires at least some conditional logic in the components. This logic exists only to make writing tests easier. In order to keep the components and prop types as simple as possible, I've marked all props required that are only option for testing purposes. In order to avoid cluttering tests with the same boilerplate props over and over again, I've simply created `defaultProps` objects that can be spread into the components.

This fixes a bug where creating and removing an entity (without reloading the page between both actions) would result in an error. When a user creates a new entity in a timeline, an ID for the entity is auto-generated. When creating a new entity, Aleph appends a HMAC signature (based on dataset ID and entity ID). The auto-generated ID and the signature form the full ID. In order to remove an entity, the full ID needs to be supplied.

Previously, when creating a new timeline item, only the auto-generated ID was stored. As a consequence, trying to remove an entity using this ID failed. Now, when creating a new item, we wait for the API response that includes the full entity ID and use that for subsequent requests.

… empty

I have kept the old implementation around while developing and have selectively used bits and pieces of the existing implementation. That is why there was a src/components/Timeline directory with the old implementation and a src/components/Timeline2 directory with the new implementation.

…hema