* Added initial AnimatedList and Item Widgets

* Use the new list in the NotificationWindow class + massive list improvements

This includes a more simplified way of calculating the item positions
relative to the fade threshold

* Added center animations

* Fixed replacing notification not scrolling to the new position (top/bottom)

* Simplified size_allocate y offset

* Fixed very large notifications fading before reaching top with small list size

* Disable card animation if GTK animations are disabled

* Removed unneeded TODO about allocation order

* Fixed input region including the fade padding