Added Tutorial class

core/src/io/anuke/mindustry/game/Tutorial.java

@@ -0,0 +1,21 @@
+package io.anuke.mindustry.game;
+
+/** Handles tutorial state. */
+public class Tutorial{
+    private TutorialStage stage = TutorialStage.values()[0];
+
+    public void reset(){
+        stage = TutorialStage.values()[0];
+    }
+
+    /** Goes on to the next tutorial step. */
+    public void next(){
+
+    }
+
+
+    public enum TutorialStage{
+        intro;
+    }
+
+}