* enable the ability to push results processing to threads
* have ClusterComm push libcurl response processing to Scheduler threads
* tuning changes from Matthew and Michael
* give new defaults to minimum thread count
* create multiple ClusterCommThreads, each with own Communicator object
* put PR notes in change log
* correct speling
* Also drain V8 queue.
* Add prio V8 to switch in canPostDirectly.
* Accept --server.minimal-threads even if maximal threads is not set.
* Reactivate stopping of threads.