Add inline node inclusion support to mod.yaml.

OpenRA.Game/Manifest.cs

@@ -73,7 +73,7 @@ namespace OpenRA
 
 		readonly string[] reservedModuleNames =
 		{
-			"Metadata", "Folders", "MapFolders", "Packages", "Rules",
+			"Include", "Metadata", "Folders", "MapFolders", "Packages", "Rules",
 			"Sequences", "ModelSequences", "Cursors", "Chrome", "Assemblies", "ChromeLayout", "Weapons",
 			"Voices", "Notifications", "Music", "Translations", "TileSets", "ChromeMetrics", "Missions", "Hotkeys",
 			"ServerTraits", "LoadScreen", "SupportsMapsFrom", "SoundFormats", "SpriteFormats",
@@ -89,7 +89,25 @@ namespace OpenRA
 		{
 			Id = modId;
 			Package = package;
-			yaml = new MiniYaml(null, MiniYaml.FromStream(package.GetStream("mod.yaml"), "mod.yaml")).ToDictionary();
+
+			var nodes = MiniYaml.FromStream(package.GetStream("mod.yaml"), "mod.yaml");
+			for (var i = nodes.Count - 1; i >= 0; i--)
+			{
+				if (nodes[i].Key != "Include")
+					continue;
+
+				// Replace `Includes: filename.yaml` with the contents of filename.yaml
+				var filename = nodes[i].Value.Value;
+				var contents = package.GetStream(filename);
+				if (contents == null)
+					throw new YamlException("{0}: File `{1}` not found.".F(nodes[i].Location, filename));
+
+				nodes.RemoveAt(i);
+				nodes.InsertRange(i, MiniYaml.FromStream(contents, filename));
+			}
+
+			// Merge inherited overrides
+			yaml = new MiniYaml(null, MiniYaml.Merge(new[] { nodes })).ToDictionary();
 
 			Metadata = FieldLoader.Load<ModMetadata>(yaml["Metadata"]);