Blender Git Loki

Feature Collada: Added AnimationCurveCache for exporting sampled animations

Details:
When exporting sampled Animations to Collada we need to create sample
data for every Animation curve. However it turns out to be extremely
slow when we repeatedly step over the entire animation for each curve.

The solution is to only step over the animation once but cache all needed
animation data in a cache. Once the animation has been processed,
all export information is located in the cache and can be easily
read from there.

The AnimationCurveCache is the first try to proof the concept.
This is work in progres and may still change a lot.