Collada animation support
Cleaned up the old dae-animation branch. Requesting a review!
The feature is fairly finished, but I have sometimes experienced glitching in animation root movement. I believe that there's still room for improvement in terms of optimizations and code quality in general.
I suggest using OSG with the following fix: https://github.com/openscenegraph/OpenSceneGraph/issues/994 as it makes things more stable.
Attached is a dae-file that can be used for testing (licensed CC0, created by Lamoot).
In action: https://youtu.be/rkxeZIKU4Po