Fix tone helper drawn on wrong octave (#746)

* Add GetCurrentBeat()

* Clamp tone helper to the octave of target note

Prevent tone helper from being off by an octave

Vocaluxe/Base/CMain.cs

@@ -571,6 +571,11 @@ namespace Vocaluxe.Base
             return CGame.GetPoints();
         }
 
+        public int GetCurrentBeat()
+        {
+            return CGame.CurrentBeat;
+        }
+
         public float GetMidRecordedBeat()
         {
             return CGame.MidRecordedBeat;