Blender Git Loki

Animation: Make it possible to keyframe to with copy-on-write

The issue was that every object tweak was doing a full copy
of original datablock onto evaluated version, and was updating
animation. This made it impossible to tweak properties which
has keyframes.

Proposed solution is to:

- Always apply animation on frame change, and when object
is explicitly tagged for animation update.

This will store original DNA value of animated property
in the f-curve.

- When applying animation in other cases, we check original
DNA value stored in f-curve with the actual original DNA
property. If they differ, it means user started to tweak
animated property, and we should skip animation.

If the value is the same, we apply animation.

This is just a first step towards proper final implementation,
but seems to be the direction we want to take.