updated twig to version 3 and added wrapper for translation via symfony/twig-bridge

Co-authored-by: Ulrik nielsen <un@ipwsystems.dk>

post.* has been added directly under assets for now, tried it
via webpack but this added a several times overhead to these
very small files, so this seemed the cleanest solution for now.
But might be improved upon.

It doesn't make much sense anyway. Makes the original templates harder to format, and browser developer tools can provide hierarchical indentation anyway. This allows us to save quite a few bytes per page, write cleaner templates, and forget about how it would look like in the resulting HTML.

re-add it and fix all templates that depended on it being unset

It was broken in previous commits. It should always stick to the bottom of the page, unless the page is long enough to not fit in the screen, so then it should just be thrown after the end of the content.

This way the code is closer to the resulting HTML, and we don't need to pass it through the "raw" filter afterwards to keep rendering the HTML.

This builds and minifies CSS and a common JS bundle, as well as copy the relevant fonts. In order to build, we now need to run "npm run build" after installing the dependencies with "npm install".

This allows more graceful fallback for untranslated languages.
Also, use `raw` filter to keep the embedded HTML working.

jquery-ui relies on jquery being loaded first.
Previous order doesn't play nice with modules that rely on jquery-ui.

- Base.twig updated

- side-menu button moved to the right
- update responsive menu for rtl languages.

- menu-link span position needs to be adjusted.
- footer should move like the rest of the page (js needed)

- Large screens: will display the dropdownmenu
- Medium & small screens will show a button (on the top right in the future)
and a menu will push the content (to left) and showing the language options.

- 3 main elements: header, content and footer.
- Header expects a logo on one corner and the language dropdown-
  menu on the other corner.
- Footer sticks to the bottom of the page if there is no content, but
  is pushed to end of the page when content exceeds window height.
- Default.css is reordered.
- Changes are device-responsive and rtl-responsive.

- Add dependencies
- Change link in script postload, base.twig
- Add function in Script.js
- Delete postload block in metadata-converter.twig and call clipboard function on button click.

add document.ready function to script.js where all the calls to selectize are made.
update base.twig. Now script.js is the last script in the list.

Fixed footer at the bottom in fixed position. (+1 squashed commit)
Squashed commits:
[27ac007] footer

Each element is defined with an id. it has its own wrap and a "row".

Change the links in the head and postload of base.twig according to the new structure and the recently added packages.

for better mobile/small form factor support (eg when using landscape) - don't specify the device-width etc
(see e.g. https://developer.apple.com/library/content/documentation/AppleApplications/Reference/SafariWebContent/UsingtheViewport/UsingtheViewport.html )

Replaces the need for `$this->data['htmlinject']`

Note that the flag in the context must be named 'clipboard',
not 'clipboard.js'. This is because the dot is an illegal symbol in
variable names in twig.