Merge changes I25effa3e,Ibb58d1aa,I92454a1b,I878d20a8,I21037b40, ...

* changes:
  Enforcing padding on the bottom of the keyguard
  Fixes that notifications were sometimes clipped on the lockscreen
  Don't reset the velocity when flinging down just because of falsing
  Don't do icon animations if we are scrolling fast
  Don't translate the notification content while scrolling
  Fixed the scrim drawing in seascape
  Placed the overflow indicator perfectly in the collapsed center
  Improved the low priority behavior with the shelf
  Improved the performance of the notification shelf
  Fixed a bug where heads up notifications had no icon
  Added possibility to use canned animation for icons