While in Quick Reading mode, reduce the time after user has finished scrolling from 500ms to 250ms.
Improved jquery filtering when marking entries as read in Quick Reading mode.

This way less jquery calls are performed and the set of affected entries is filtered as soon as possible.
Added not-null constraints and default values for many database columns.
Added new controller and route to retrieve configuration data for the currently authenticated user.

Currently we only return the quick_reading attribute for the user, but in the future other values will likely be returned.
When loading the read view, user configuration is requested via AJAX. Quick Reading mode (mark entries as read as soon as they are scrolled past the viewport) is enabled only if the user has the quick_reading attribute set to true.

This means that the Quick Reading mode is feature-complete (user can enable or disable it in his registration edit view).

Not yet implemented: some acceptance tests, or at least smoke tests, for this functionality.