Add new parameter 'itemsPerRow'. This limits the grid columns used, 
making items move to the next row if overextending.

Also simplify component structure.

This is only useful in CompoundElements. So use checks for that class 
instance.

Now always shows the values as rich text (which works because basic text 
is valid html).

Also remove some unused fields.

Initialize to null, to be able to differentiate in the props panel.

Also improve props panel layout by always showing all fields and 
disabling them if needed instead of hiding them.

Fix translation.

Also add it to the likert row dialog.

#112

Also refactor properties panel and ToggleButton class logic for striking 
values. This now relies more on CSS classes provided by Material instead 
of doing finetuned logic my ourselves. This also allows showing the 
correct preview in the editor.

#287

- Move props to separate files
- Fix typing

Also improve media element property control layout.

#204

Now the dialog scrolls and the buttons at the bottom can be reached even 
on low viewport height.

#294

Casting to ButtonElement caused issues where changed values were not 
recognized by inputs.

#280

The TipTap editor needs a setting to be able to read base64 encoded 
images.

Also improve method name.

#297

#298

..instead of multiple methods doing almost the same stuff.

More german quoting characters.

#209

There was at least one bug, where entering a number could create a list 
with wrong styles. This is the easy fix by disabling all that, instead 
of fixing it, which might bo out of our jurisdiction anyway.

#226

Better icons and reordered elements.

#267

- Missing type inforamtion as constructor parameter
- Also the new ID generation mechanism uses the type of the element to 
request an ID from the the IDManager. Here was a mismatch, where the 
type is 'likert-row', but the IDManager only knew 'likert_row'. This is 
now files all IDs use hyphens instead of underscores.

Remove 'any's be adding proper types and using 'never'.

Now properly finds all normal and simple drop lists.
This is achieved by a new method of unit all it's sub-components, which 
returns all contained elements with and optional type filter.

Also improve (still not very pretty) styling of the drop list props 
panel.

#260 #259