Pager should be configured by items per page, not number of pages.

In the current implementation, the pager is configured to a maximum number of pages. This number of pages is then used to determine how many items should be shown per page. This is the exact opposite of what a pager is supposed to do (at least in Drupal).

Attached patch changes this behavior to a configuration of the maximum number of items per page. The formatter then determines how many pages it should show based on that.