add Game.AddChatLine to the new Lua API

OpenRA.Mods.RA/OpenRA.Mods.RA.csproj

@@ -543,6 +543,7 @@
     <Compile Include="Widgets\Logic\DebugMenuLogic.cs" />
     <Compile Include="Widgets\LabelWithTooltipWidget.cs" />
     <Compile Include="ProductionQueueFromSelection.cs" />
+    <Compile Include="Scripting\Global\MediaGlobal.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenRA.Game\OpenRA.Game.csproj">

OpenRA.Mods.RA/Scripting/Global/MediaGlobal.cs

@@ -0,0 +1,29 @@
+#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.Drawing;
+
+namespace OpenRA.Scripting
+{
+	[ScriptGlobal("Media")]
+	public class MediaGlobal : ScriptGlobal
+	{
+		public MediaGlobal(ScriptContext context) : base(context) { }
+
+		[Desc("Display a text message to the player.")]
+		public void DisplayMessage(string text, string prefix = "Mission") // TODO: expose HSLColor to Lua and add as parameter
+		{
+			if (string.IsNullOrEmpty(text))
+				return;
+
+			Game.AddChatLine(Color.White, prefix, text);
+		}
+	}
+}