fix #436 bridges in wrong place in render sequence

OpenRA.Game/Graphics/WorldRenderer.cs

@@ -77,6 +77,9 @@ namespace OpenRA.Graphics
 			Game.Renderer.EnableScissor(bounds.Left, bounds.Top, bounds.Width, bounds.Height);
 
 			terrainRenderer.Draw(this, Game.viewport);
+			foreach (var a in world.traitDict.ActorsWithTraitMultiple<IRenderAsTerrain>(world))
+				foreach (var r in a.Trait.RenderAsTerrain(a.Actor))
+					r.Sprite.DrawAt(r.Pos, this.GetPaletteIndex(r.Palette), r.Scale);
 
 			foreach (var a in world.Selection.Actors)
 				if (!a.Destroyed)

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -36,6 +36,7 @@ namespace OpenRA.Traits
 
 	public interface ITick { void Tick(Actor self); }
 	public interface IRender { IEnumerable<Renderable> Render(Actor self); }
+
 	public interface IIssueOrder
 	{
 		IEnumerable<IOrderTargeter> Orders { get; }
@@ -202,6 +203,7 @@ namespace OpenRA.Traits
 
 	public interface IPostRenderSelection { void RenderAfterWorld(WorldRenderer wr, Actor self); }
 	public interface IPreRenderSelection { void RenderBeforeWorld(WorldRenderer wr, Actor self); }
+	public interface IRenderAsTerrain { IEnumerable<Renderable> RenderAsTerrain(Actor self); }
 
 	public struct Target		// a target: either an actor, or a fixed location.
 	{