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- RenderNameTag has been replaced by WithNameTagDecoration, which is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/Cargo.cs

@@ -26,9 +26,6 @@ namespace OpenRA.Mods.Common.Traits
 		[Desc("The maximum sum of Passenger.Weight that this actor can support.")]
 		public readonly int MaxWeight = 0;
 
-		[Desc("Number of pips to display when this actor is selected.")]
-		public readonly int PipCount = 0;
-
 		[Desc("`Passenger.CargoType`s that can be loaded into this actor.")]
 		public readonly HashSet<string> Types = new HashSet<string>();
 
@@ -88,7 +85,7 @@ namespace OpenRA.Mods.Common.Traits
 		public object Create(ActorInitializer init) { return new Cargo(init, this); }
 	}
 
-	public class Cargo : IPips, IIssueOrder, IResolveOrder, IOrderVoice, INotifyCreated, INotifyKilled,
+	public class Cargo : IIssueOrder, IResolveOrder, IOrderVoice, INotifyCreated, INotifyKilled,
 		INotifyOwnerChanged, INotifySold, INotifyActorDisposing, IIssueDeployOrder,
 		ITransformActorInitModifier
 	{
@@ -379,30 +376,6 @@ namespace OpenRA.Mods.Common.Traits
 				t.TurretFacing = facing.Value.Facing + Info.PassengerFacing;
 		}
 
-		public IEnumerable<PipType> GetPips(Actor self)
-		{
-			var numPips = Info.PipCount;
-
-			for (var i = 0; i < numPips; i++)
-				yield return GetPipAt(i);
-		}
-
-		PipType GetPipAt(int i)
-		{
-			var n = i * Info.MaxWeight / Info.PipCount;
-
-			foreach (var c in cargo)
-			{
-				var pi = c.Info.TraitInfo<PassengerInfo>();
-				if (n < pi.Weight)
-					return pi.PipType;
-				else
-					n -= pi.Weight;
-			}
-
-			return PipType.Transparent;
-		}
-
 		public void Load(Actor self, Actor a)
 		{
 			cargo.Add(a);