added placeholder cpp files to the project

Source/LevelUnderNineEditor.Target.cs

@@ -0,0 +1,15 @@
+// Fill out your copyright notice in the Description page of Project Settings.
+
+using UnrealBuildTool;
+using System.Collections.Generic;
+
+public class LevelUnderNineEditorTarget : TargetRules
+{
+	public LevelUnderNineEditorTarget(TargetInfo Target) : base(Target)
+	{
+		Type = TargetType.Editor;
+		DefaultBuildSettings = BuildSettingsVersion.V7;
+
+		ExtraModuleNames.AddRange( new string[] { "LevelUnderNine" } );
+	}
+}