Detect Blender animations/actions that aren't supported by SMF

[bartteunis]

Because it makes use of dual quaternions, SMF is somewhat limited in which animations it can export: scaling bones during animation isn't possible.
Try to come up with a way to "detect" this. A straightforward way to do this seems to be to check if an action has any keyframes on bone scale but it may be more complicated than this.

Figure out how to detect this.