Priority of pieces

adding a weight to pieces we got from the (super-) seeder. thoseones get a higher prior for the upload-queue of peers and clients that ask for them are prefered but still by the rules of the ratio-controller.

What and why?

To get a visible overview for important pieces we keep currently of the swarm.

I add it to the total values in the peersview below the "interested" field.

see the example picture

when you leave the swarm now this pieces are missed mostly. When you have some reasons to leave the swarm in time than be fair and wait that the value is zero or close to. You can ban the seeder in time before you leave that will decreasing the amount of important pieces you take away of the swarm.