Prevent crash when using QuantizedFacings: 0 on BodyOrientation.

This override allows quantization to be disabled, and is used by the TS mod as the voxel based actors can be rotated to any orientation/facing. To prevent a divide by zero error for these actors, we need to return early from QuantizeFacing just like we do in QuantizeOrientation.

However, when QuantizedFacings is not explicitly set to zero, we still want to catch errors when artwork sequences have zero facings. The new check would cause such errors to be hidden. To prevent this add some exceptions with a detailed error message.

OpenRA.Mods.Cnc/Traits/ClassicFacingBodyOrientation.cs

@@ -18,6 +18,10 @@ namespace OpenRA.Mods.Cnc.Traits
 	{
 		public override WAngle QuantizeFacing(WAngle facing, int facings)
 		{
+			// Quantization disabled
+			if (facings == 0)
+				return facing;
+
 			return Util.ClassicQuantizeFacing(facing, facings);
 		}