* divides the area where the scroll should be triggered by 2
* uses the minimum value of the above and 300

The background job will now be executed in chunks of 500 users all 10 minutes.

The public page now uses the public.php/webdav endpoint.

Also enabled more file operations like rename, move, delete and create
folder from the public page, which are now all possible thanks to the
public.php/webdav endpoint.

- Clicking a file row or selecting it will open the sidebar.
- When sidebar is open, its contents update with the last selection.
- Dragging doesn't open the sidebar but does update its contents if it was
open already.
- Switching folders closes the sidebar.
- Close sidebar when highlighted file got deleted/removed from list

* ref #12877

* removed the setDefault call because then it will always be
  reshown
  * was added with ba475d48
* fixes #18208

* getstoragestats.php returns now the owner and it's display name
* show proper storage stats notifications for shared folders

Since the thumbnail is now in a div, the code that tries to change the
thumbnail have been adapted here as well.

Added namespaces so that JSDoc can find them.
Fixed a few warnings.
Improved some comments.

When dropping files onto a read-only folder, a notification
is now shown instead of attempting to upload.

This for both the drag for upload and drag from inside the file list
cases.

Now binding properly with the file list instance object.

For some reason IE8 didn't like the sort function, so using the one from
underscore instead.