Queues logging

[roman-mazur]

Proposal.

Queues can be visualized

name   | processing | line
-----------------------------------------------
queue1 | task3      | task1 <- task2
queue2 | task10     | task43 <- task42 <- task0

We can dump the state with goro.dump(Writer).
Also there is a Dumper implements GoroListener that dumps the state whenever task is added/started/finished.
GoroService has static setDebug(true|false) method that leads to registering Dumper in debug mode.