Added two diplomacy functions to lua

...and sneaked into AUTHORS

OpenRA.Mods.RA/Scripting/Properties/DiplomacyProperties.cs

@@ -0,0 +1,39 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 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 System;
+using Eluant;
+using OpenRA.Network;
+using OpenRA.Scripting;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA.Scripting
+{
+	[ScriptPropertyGroup("Diplomacy")]
+	public class DiplomacyProperties : ScriptPlayerProperties
+	{
+		public DiplomacyProperties(ScriptContext context, Player player)
+			: base(context, player) { }
+
+		[Desc("Returns true if the player is allied with the other player.")]
+		public bool IsAlliedWith(Player targetPlayer)
+		{
+			return player.IsAlliedWith(targetPlayer);
+		}
+
+		[Desc("Changes the current stance of the player against the target player. " +
+			"Allowed keywords for new stance: Ally, Neutral, Enemy.")]
+		public void SetStance(Player targetPlayer, string newStance)
+		{
+			var emergingStance = Enum<Stance>.Parse(newStance);
+			player.SetStance(targetPlayer, emergingStance);
+		}
+	}
+}