[feature request] Button to switch tracks/decks 1 & 2 around in export mode

I am often wanting to swap tracks 1 and 2 over, and it would be so much simpler just to have a button to action this rather than having to drag and drop each time.

Reasons I might want to be swapping them over could be:

• for getting one of the tracks back into the single track/editing view
• for shuffling track 2 into track 1 slot when going through a mix playlist and working out how tracks best fit together, etc.