brought back the MoveFlash

closes #2592
StyleCop cleanup
removed unused Iron Curtain palette
separate TargetFlash from DrawLineToTarget
only use Self for internal self references
avoid additional layers of abstraction
don't stack flashes and filter non unit actor related orders
loop all orders only once
StyleCop cleanup
update changelog
Merge pull request #3999 from Mailaender/moveflash

Brought back the MoveFlash