Merge branch 'animate-layout-manager' into ebassi-next

* animate-layout-manager:
  layout-manager: Document the animation support
  layout-manager: Rewind the timeline in begin_animation()
  box-layout: Remove the allocations hash table
  docs: Clean up the README file
  layout: Let begin_animation() return the Alpha
  box-layout: Add knobs for controlling animations
  box-layout: Animate layout properties
  layout: Add animation support to LayoutManager
  Add ActorBox animation methods

diff --cc clutter/clutter-actor.c
Simple merge

diff --cc doc/reference/clutter/clutter-sections.txt
Simple merge

diff --cc tests/interactive/test-box-layout.c
Simple merge