Fix fc::thread to set the thread name in the Debugger when the name is set after thread construction.
When terminating a thread, cancel any tasks that have been schedule()d or async()ed but have not yet started executing.
When canceling a task blocked on a fc::mutex, notify the thread to reschedule the task to allow it to clean up the mutex's block list.
Fix a bug in managing the recursive lock count when tasks block on a fc::mutex
Reorder the code that manages the hard links for log files to avoid an exception generated by unlinking a locked file on Windows.
- we were canceling tasks that hadn't been canceled, because the canceled flag was left set to true and the next task assigned to the context then became canceled as soon as it yielded
- we were resumeing blocked tasks before they should have resumed, because their blocking_promises list wasn't cleared and they were unblocking because the erroneous promises were fulfilled
As a debugging aid, we also record the cancellation reason whenever a task is canceled, and include that in the canceled_exception (this is only enabled in debug builds)
Something about the stacks created by boost::context prevents global structured exception handlers
from being called. This allows the user to register a handler which will be called when there
is an unhandled structured exception in async task.
