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.
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.
