Add support for rearranging tracks from the UI

[saagarjha]

Maybe there is a way to do this but I couldn't find it. In my head I would expect there to be a grab handle somewhere on the process/thread list and that would let me move things to a new order.

[LalitMaganti]

So in fact this is a very interesting idea. It's actually very intentional that in the default view of the trace that the UI has full control over it. If you were to create a "workspace" (a feature of the UI which lets you basically get access to a blank canvas to build what you want) you can rearrange tracks freely.

One way out of this might be we allow rearranging tracks but we allow you to get back to a view of the trace immediately after you loaded it (which is what the motivation was for not rearranging tracks in the first place I think).