Add terminating newline to yaml strings.

OpenRA.Game/MiniYaml.cs

@@ -28,7 +28,8 @@ namespace OpenRA
 
 		public static string WriteToString(this MiniYamlNodes y)
 		{
-			return y.ToLines().JoinWith("\n");
+			// Remove all trailing newlines and restore the final EOF newline
+			return y.ToLines().JoinWith("\n").TrimEnd('\n') + "\n";
 		}
 
 		public static IEnumerable<string> ToLines(this MiniYamlNodes y)

OpenRA.Test/OpenRA.Game/MiniYamlTest.cs

@@ -269,7 +269,8 @@ Parent: # comment without value
 
 			var strippedYaml = @"Parent:
 	First: value containing a \# character
-	Second: value".Replace("\r\n", "\n");
+	Second: value
+".Replace("\r\n", "\n");
 
 			var result = MiniYaml.FromString(yaml).WriteToString();
 			Assert.AreEqual(strippedYaml, result);