Added in code for Tech Levels using prereqs

and fixed up some kinks of the old system

OpenRA.Mods.RA/Player/ProvidesTechPrerequisite.cs

@@ -0,0 +1,51 @@
+#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 System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using OpenRA.Primitives;
+using OpenRA.Traits;
+using OpenRA.FileSystem;
+
+namespace OpenRA.Mods.RA
+{
+	public class ProvidesTechPrerequisiteInfo : ITraitInfo
+	{
+		public readonly string Name;
+		public readonly string[] Prerequisites = {};
+
+		public object Create(ActorInitializer init) { return new ProvidesTechPrerequisite(this, init); }
+	}
+
+	public class ProvidesTechPrerequisite : ITechTreePrerequisite
+	{
+		ProvidesTechPrerequisiteInfo info;
+		bool enabled;
+		static readonly string[] NoPrerequisites = new string[0];
+
+		public string Name { get { return info.Name; } }
+
+		public IEnumerable<string> ProvidesPrerequisites
+		{
+			get
+			{
+				return enabled ? info.Prerequisites : NoPrerequisites;
+			}
+		}
+
+		public ProvidesTechPrerequisite(ProvidesTechPrerequisiteInfo info, ActorInitializer init)
+		{
+			this.info = info;
+			this.enabled = info.Name == init.world.LobbyInfo.GlobalSettings.TechLevel;
+		}
+	}
+}