Move Guard, CashTrickler, Explodes, SelfHealing, Sellable and Crushable to Mods.Common.

Extract Guardable trait from Guard into own file.

OpenRA.Mods.Common/Traits/Guardable.cs

@@ -0,0 +1,22 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2015 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. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("This unit can be guarded (followed and protected) by a Guard unit.")]
+	public class GuardableInfo : TraitInfo<Guardable>
+	{
+		public readonly int Range = 2;
+	}
+
+	public class Guardable { }
+}