CoroutineUtil: minor clean-up based on Resharper feedback
DreamActivityDescription:
* capture date-time at creation and don't modify thereafter
* since we're updating a single string reference, we don't need to lock it, but we do treat it as volatile
AsyncUtil:
* added method to obtain stack trace from another thread
* added tracking of threads created so they can be enumerated
DispatchThread: use new AsyncUtil.CreateThread() method
GlobalClock: use new AsyncUtil.CreateThread() method
DreamHostService: added GET:status/timers feature