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- RenderNameTag has been replaced by WithNameTagDecoration, which is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

@@ -146,8 +146,9 @@ namespace OpenRA.Mods.Common.Traits
 				var xy = wr.Viewport.ViewToWorld(Viewport.LastMousePos);
 				foreach (var unit in power.UnitsInRange(xy))
 				{
-					var bounds = unit.TraitsImplementing<IDecorationBounds>().FirstNonEmptyBounds(unit, wr);
-					yield return new SelectionBoxAnnotationRenderable(unit, bounds, Color.Red);
+					var decorations = unit.TraitsImplementing<ISelectionDecorations>().FirstEnabledTraitOrDefault();
+					foreach (var d in decorations.RenderSelectionAnnotations(unit, wr, Color.Red))
+						yield return d;
 				}
 			}