Modified animation keyframes to be structs rather than classes (reduced allocations, at the cost of more copying - copying cost can be worked around by carefully using references and pointers within the animation system)

Signed-off-by: Martin Evans <martindevans@gmail.com>
Separated animation system in Animated (takes bone transforms, updates skeleton) and AniamtionQueue (handles clips and playback and crossfading etc)

Signed-off-by: Martin Evans <martindevans@gmail.com>