DistributedTaskPart.equals() implementation is wrong

DistributedExecutorService.submitEverywhere() returns a list of futures, one future for each targeted node. Because of how DistributedTaskPart.equals() is implemented, all the futures in the list appear to be equal, even though their target node is different and their result will also be different.

The simplest fix would be to remove the equals() and hashCode() overloads from DistributedTaskPart.