* animation-improvements:
[docs] Add ClutterAnimatable to the API reference
Add license notice to ClutterAnimation files
[docs] Update the ClutterAnimation section
[animation] Extend ClutterAnimation support to all objects
[animation] Use ClutterAnimatable inside Animation
[animation] Add ClutterAnimatable
[animation] Allow registering custom progress function
[animation] Interval::compute_value should return a boolean
Animate ClutterColor properties
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