ClipboardJS is initialised once in the bundle for class="copy",
not initialised on each page that uses it.

This is because some templates, e.g. errror, expect to be able to
include them. This fixes e.g. the No State error page.

No need to have a postload for clipboard.js in templates.
Use the class "clipboard-btn" and match the data-clipboard-target with the right ID
(or other DOM-element).

- Add class pure-button-red instead of overwriting primary
- Create a group of 2 button-elements where one is hollow, useful
to show input-files or error-ids.
- Update templates accordingly

- Change metadatabox to a general code-box, code-box-content and code-box-title
- Change xmlarea to text-area
- Update templates that where using old classes