New scheduler

I understand that a new scheduler is not a new feature and might be less interesting to hear about. However it is quite an important structural change in ShadowTrackr that allows scaling up further and improving performance. It should be able to speed up the discovery process too.

For such an important change the "big bang" scenario doesn't feel right, so as of yesterday just two DNS discovery algorithms have moved to the new scheduler. I will be monitoring them closely and if all goes well move a few other queues over to the new scheduler.