scene.cpp : fix animation bug
scene.cpp : fix animation bug

Scene::
- Set _animationTime to 0 a construction
- Copy __activeAnimatables (vector<AnimatablePtr>) before looping inside _animate()
 because activeAnimatable->_animate can remove items from _scene->_activeAnimatables

samdauwe/BabylonCpp,samdauwe/BabylonCpp,samdauwe/BabylonCpp,samdauwe/BabylonCpp