Add a per-player handicap option to the lobby.

Handicaps reduce unit health, firepower, and build speed.

OpenRA.Mods.Common/Traits/Multipliers/HandicapProductionTimeMultiplier.cs

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+#region Copyright & License Information
+/*
+ * Copyright 2007-2020 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 System.Collections.Generic;
+using System.Linq;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("Modifies the production time of this actor based on the producer's handicap.")]
+	public class HandicapProductionTimeMultiplierInfo : TraitInfo<HandicapProductionTimeMultiplier>, IProductionTimeModifierInfo
+	{
+		int IProductionTimeModifierInfo.GetProductionTimeModifier(TechTree techTree, string queue)
+		{
+			// Equivalent to the build speed handicap from C&C3:
+			//  5% handicap = 105% build time
+			// 50% handicap = 150% build time
+			// 95% handicap = 195% build time
+			return 100 + techTree.Owner.Handicap;
+		}
+	}
+
+	public class HandicapProductionTimeMultiplier { }
+}