Add an external condition whitelist.

OpenRA.Mods.Common/Traits/Upgrades/ExternalConditions.cs

@@ -0,0 +1,25 @@
+#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 OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("Lists conditions that are accepted from external sources (Lua, warheads, etc).",
+		"Externally granted conditions that aren't explicitly whitelisted will be silently ignored.")]
+	public class ExternalConditionsInfo : TraitInfo<ExternalConditions>
+	{
+		[UpgradeGrantedReference]
+		public readonly string[] Conditions = { };
+	}
+
+	public class ExternalConditions { }
+}