Leave only one track type, WIP: track deletion.

Source/ProjectController.cs

@@ -7,12 +7,18 @@ namespace AudioEditor;
 public partial class ProjectController : Node
 {
     [Signal] public delegate void AudioClipDroppedEventHandler(Vector2 atPosition, string path, string clipName, double startTime, double endTime);
+    [Signal] public delegate void OnTrackDeletedEventHandler(int trackIdx);
 
     public override void _Ready()
     {
         GetWindow().FilesDropped += FilesDropped;
     }
 
+    public void DeleteTrack(int trackIdx)
+    {
+
+    }
+
     public void CreateAudioClipPreview(Control audioClip)
     {
         // GD.Print(audioClip.Clas());