Switch to the running animation only above a certain ratio of the walk speed.

Following D3221/rP24396, units switch to the 'run' animation when moving faster than their walkspeed.
This makes formations 'flickery' because units often move slightly faster than their walkspeed when the formation rotate slightly, which happens often. It looks fairly bad.

This switches to the running animation halfway through, though a more general system would be more desirable.

Approved By: Angen

Reviewed By: bb

Differential Revision: https://code.wildfiregames.com/D3224