Rework decoration renderable traits:

- Removed implicit pip definitions and IPips interface.
  New decoration traits have been added to render them.
  Pip types are no longer hardcoded in OpenRA.Game.

- Decoration rendering is now managed by SelectionDecorations(Base),
  which allows us to remove assumptions about the selection box
  geometry from the decoration traits.

- RenderNameTag has been replaced by WithNameTagDecoration, which is
  an otherwise normal decoration trait.

- Unify the configuration and reduce duplication between traits.

- Removed hardcoded references to specific selection box renderables.

- Remove legacy cruft.

OpenRA.Mods.Common/Traits/Interactable.cs

@@ -17,7 +17,7 @@ using OpenRA.Traits;
 namespace OpenRA.Mods.Common.Traits
 {
 	[Desc("Used to enable mouse interaction on actors that are not Selectable.")]
-	public class InteractableInfo : ITraitInfo, IMouseBoundsInfo, IDecorationBoundsInfo
+	public class InteractableInfo : ITraitInfo, IMouseBoundsInfo
 	{
 		[Desc("Defines a custom rectangle for mouse interaction with the actor.",
 			"If null, the engine will guess an appropriate size based on the With*Body trait.",
@@ -32,7 +32,7 @@ namespace OpenRA.Mods.Common.Traits
 		public virtual object Create(ActorInitializer init) { return new Interactable(this); }
 	}
 
-	public class Interactable : INotifyCreated, IMouseBounds, IDecorationBounds
+	public class Interactable : INotifyCreated, IMouseBounds
 	{
 		readonly InteractableInfo info;
 		IAutoMouseBounds[] autoBounds;
@@ -72,7 +72,7 @@ namespace OpenRA.Mods.Common.Traits
 			return Bounds(self, wr, info.Bounds);
 		}
 
-		Rectangle IDecorationBounds.DecorationBounds(Actor self, WorldRenderer wr)
+		public Rectangle DecorationBounds(Actor self, WorldRenderer wr)
 		{
 			return Bounds(self, wr, info.DecorationBounds ?? info.Bounds);
 		}