Initial attempt at MD5 animation loading

Files are parsed and loaded, and interpolating between
to frames will return the resulting, shader-ready,
FrameSkeleton which contains a list of joint transforms.

MD5Anim also registered for JSON resource types.
Added animation class

This will be used to keep per-instance animation matricies.

The animations will be updated via RenderSystem for now
and later on, if needed, an animation system.

Renderable has an animation, as well as, loading the animation
during initialization.
Graphics now understands how to use animations

These are updated during HandleWork. During the
render loop they are referenced from the MaterialGroup
tree.

Additional shader parameters have been setup for:
-animated (a uniform int if the renderable has animation)
-animation_matrix (a uniform mat4 array of transformed joint matricies).
Added deactivating texture units

This was allowing untexture renderable to
be textured via the last active texture.

Fixed minor build issues.
Fixed a memory issue by using assign instead of insert on a vector
Merge branch 'feature-md5-animation' into develop

Updated assets