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