MSM5232 instrument editor

the instrument editor for MSM5232 consists of these macros:

• Volume: volume sequence.
• only has effect when the envelope mode of a group is set to External.
• Arpeggio: pitch sequence.
• Group Ctrl: group control sequence:
• sustain: enable sustain mode.
• 2': enable 2' overtone.
• 4': enable 4' overtone.
• 8': enable 8' overtone.
• 16': enable 16' overtone.
• Group Attack: set attack rate of group.
• Group Decay: set decay rate of group.
• Noise: toggle noise mode.