make more activities cancelable. remove many uses of CurrentActivity is T

OpenRA.Mods.RA/Activities/IdleAnimation.cs

@@ -6,11 +6,11 @@
  * as published by the Free Software Foundation. For more information,
  * see LICENSE.
  */
-#endregion
-
-using System;
+#endregion
+
+using System.Collections.Generic;
+using OpenRA.Mods.RA.Render;
 using OpenRA.Traits;
-using OpenRA.Mods.RA.Render;
 
 namespace OpenRA.Mods.RA.Activities
 {
@@ -51,5 +51,10 @@ namespace OpenRA.Mods.RA.Activities
 			else
 				NextActivity = activity;
 		}
+
+		public IEnumerable<float2> GetCurrentPath()
+		{
+			yield break;
+		}
 	}
 }