Resolve "Update: ItemSelectModal"

Closes #550

Depends on !516+!

Most of the work was already implicitly done in other issues, thanks! – The main thing I did, was moving the modal to bengal theme.

I changed the wording a bit and removed the original template; I did not restore the ionic template, too old, too ionic. Instead I added an Error message to the original template, such that if the themes fails to provide the modal, we get a hint about, where the error lies.

The modal is a bit too wide for my screen; that's due to width of the item tags. That will be the subject of an upcoming issue :)