New internal music player and note viewer

[list] [*] You can now use the MuGen internal music player to play back generated songs. [*] A new Note Viewer will show in real time the notes played in each channel. [*] You can also click the new 'stop music' button to stop playback at any time. [*] Added new options for melody direction change and melody note max deviation from root for more melody control [*] FX notes will now respect current scale and key. [*] Fixed bug where the wrong instrument was shown for a channel. [*] Other fixes [/list]