Merge changes from topic 'dyson'
* changes:
Improved the transformation to an icon further
Fixed a bug where the last notification could be invisible / faded
Adapted the shelf color when transitioning
Fully removed the bottom stack
Fixed a bug where the first notification was cut off
Fixed a a bug where clear all was invisible
Fixed a flicker when expanding quicksettings on the lockscreen
Added appear and disappear animations for the shelf icons
Implemented a nicer transition when the icons overflow
Added the possibility to animate X and refactoring
Modified heads up experience
Fixed a bug with not-gone notifications
Adapted the animation to the full shade
Fixed the lockscreen positon with a single notificaton
Made heads up work again
Fixed the transformation into the shelf
Used different curve for the icons when expanding
Refactored the stack animation logic
Refactored shelf transformation code to support animations
Improved the transition into the statusbar
Adapted the icon transformation into the shelf
Fixed the appearance of the shelf on the lockscreen
Introduced the Notification shelf
Refactored the viewstates for more modularity