Rearrange items on Audio Editor

[RobDavenport]

Currently, it's not possbile to move items around on the AudioList. This can cause quite the usability issue when users want to create many instruments, chains, etc, but are stuck with the original order they used with.

It would be good to have the option of re-arranging things things.

It's also important that when something is changed, the resulting references are updated. IE, if an instrument is moved to a different index, all of the phrases which reference that instrument should be updated to the new index. Same applies for chains, phrases, and songs.