Improve crossfading in JuK trunk to not sound like a catastrophe for the first half second. I think the order of inserting effects into the audio path has something to do with it, so I've reordered everything to be ready before starting the next track.

In addition you shouldn't get huge volume jumps when crossfading rapidly and I've improved the memory allocation lifetimes.

Unfortunately you still sometimes get a bit of high-volume at the beginning of the next track but I don't think that is juk's fault.