New GUI

[cuikho210]

• [x] NoteOn callback
• [x] Start/pause/stop player
• [x] Highlight mml
• [x] Player: On mml end callback
• [x] Match instrument icon
• [x] Loading status
• [x] Scroll to highlight

[cuikho210]

Ahihi

[cuikho210]

Kiểm tra lại lỗi mất instrument khi chạy split, merge, equalize