TODO...
Save/load tracks
Mute/Solo - I would like to be able to mute and solo individual tracks. Muting a track should prevent its enabled steps from playing. Soloing a track should internally mute all other tracks.
Nudge - I would like to be able to nudge any steps in a particular track one step to the left or right.
Clear - I would like to be able to completely clear the enabled steps on a particular track.
Velocity - I would like to be able to toggle each step between high and normal volume.
