DataTable improvements

There are some small issues in the new Datatable component:

• Sometimes 'Load more' is shown although there are no further results.
• Horizontal scrollbar at the bottom of the page should be hidden: currently, is it always shown but never active. Not sure what "page", but it should be easy to spot.

There are some issues in how the new Datatable component is used (there are multiple usages):

• The result list could have a bit wider margin, especially at the bottom.
• The table does not currently show the number of loaded results: it only shows the number of available results. I would add this in the header, e.g "Showing X/Y results."
• I would increase the number of initially displayed results and the number of results loaded when pressing Load more. E.g. 20 and 20.