Moved FlashTarget to Mods.Common

There is nothing remaining in OpenRA.Game using this.

OpenRA.Mods.Common/Effects/FlashTarget.cs

@@ -0,0 +1,56 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2016 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Collections.Generic;
+using System.Linq;
+using OpenRA.Effects;
+using OpenRA.Graphics;
+
+namespace OpenRA.Mods.Common.Effects
+{
+	public class FlashTarget : IEffect
+	{
+		Actor target;
+		Player player;
+		int remainingTicks;
+
+		public FlashTarget(Actor target, Player asPlayer = null, int ticks = 4)
+		{
+			this.target = target;
+			player = asPlayer;
+			remainingTicks = ticks;
+			target.World.RemoveAll(effect =>
+			{
+				var flashTarget = effect as FlashTarget;
+				return flashTarget != null && flashTarget.target == target;
+			});
+		}
+
+		public void Tick(World world)
+		{
+			if (--remainingTicks == 0 || !target.IsInWorld)
+				world.AddFrameEndTask(w => w.Remove(this));
+		}
+
+		public IEnumerable<IRenderable> Render(WorldRenderer wr)
+		{
+			if (target.IsInWorld && remainingTicks % 2 == 0)
+			{
+				var palette = wr.Palette(player == null ? "highlight" : "highlight" + player.InternalName);
+				return target.Render(wr)
+					.Where(r => !r.IsDecoration)
+					.Select(r => r.WithPalette(palette));
+			}
+
+			return SpriteRenderable.None;
+		}
+	}
+}