Formation controllers now display their movement paths when enabling
UnitMotion debug overlay.
Key changes:
- Formation controllers show long paths in blue and short paths in green
- Formation controllers path are rendered if selecting
some of the formation's members
- Prevent the gui from making redundant calls to SetMotionDebugOverlay
Existing limitations (not regressions):
- Paths are often cleared before entities complete them
- Formation members have short paths that rarely get rendered