don't hardcode hidden mods

OpenRA.Game/ModMetadata.cs

@@ -23,6 +23,7 @@ namespace OpenRA
 		public string Description;
 		public string Version;
 		public string Author;
+		public bool Hidden;
 
 		static Dictionary<string, ModMetadata> ValidateMods()
 		{

OpenRA.Mods.Common/Widgets/Logic/ModBrowserLogic.cs

@@ -65,7 +65,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 			};
 
 			sheetBuilder = new SheetBuilder(SheetType.BGRA);
-			allMods = ModMetadata.AllMods.Values.Where(m => m.Id != "modchooser")
+			allMods = ModMetadata.AllMods.Values.Where(m => !m.Hidden)
 				.OrderBy(m => m.Title)
 				.ToArray();
 

mods/modchooser/mod.yaml

@@ -2,6 +2,7 @@ Metadata:
 	Title: Mod Chooser
 	Version: {DEV_VERSION}
 	Author: The OpenRA Developers
+	Hidden: true
 
 Folders:
 	.