Add map support for inline base64 fluent messages.

This enables the RC to parse and share custom messages
as part of the map's custom rules without any additional
API changes.

OpenRA.Mods.Common/Lint/CheckFluentReferences.cs

@@ -71,6 +71,11 @@ namespace OpenRA.Mods.Common.Lint
 					}
 				}
 			}
+
+			if (map.FluentMessageDefinitions.Nodes.Length > 0)
+				emitWarning(
+					$"Lint pass ({nameof(CheckFluentReferences)}) lacks the know-how to test inline map fluent messages " +
+					"- previous warnings may be incorrect");
 		}
 
 		void ILintPass.Run(Action<string> emitError, Action<string> emitWarning, ModData modData)

OpenRA.Mods.Common/UtilityCommands/ExtractMapRules.cs

@@ -47,6 +47,35 @@ namespace OpenRA.Mods.Common.UtilityCommands
 			Console.WriteLine(output.ToLines(key).JoinWith("\n"));
 		}
 
+		static void MergeAndPrintFluentMessages(Map map, string key, MiniYaml value)
+		{
+			var nodes = new List<MiniYamlNode>();
+			var includes = new List<string>();
+			if (value != null && value.Value != null)
+			{
+				// The order of the included files matter, so we can defer to system files
+				// only as long as they are included first.
+				var include = false;
+				var files = FieldLoader.GetValue<string[]>("value", value.Value);
+				foreach (var f in files)
+				{
+					include |= map.Package.Contains(f);
+					if (include)
+					{
+						nodes.Add(new MiniYamlNode("base64", Convert.ToBase64String(map.Open(f).ReadAllBytes())));
+					}
+					else
+						includes.Add(f);
+				}
+			}
+
+			if (value != null)
+				nodes.AddRange(value.Nodes);
+
+			var output = new MiniYaml(includes.JoinWith(", "), nodes);
+			Console.WriteLine(output.ToLines(key).JoinWith("\n"));
+		}
+
 		[Desc("MAPFILE", "Merge custom map rules into a form suitable for including in map.yaml.")]
 		void IUtilityCommand.Run(Utility utility, string[] args)
 		{
@@ -60,6 +89,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 			MergeAndPrint(map, "Voices", map.VoiceDefinitions);
 			MergeAndPrint(map, "Music", map.MusicDefinitions);
 			MergeAndPrint(map, "Notifications", map.NotificationDefinitions);
+			MergeAndPrintFluentMessages(map, "Translations", map.FluentMessageDefinitions);
 		}
 	}
 }