Mrntt now has the event loop structure required to orderly shut itself
down when it itself generates an exception. We can now post a message
within the catch{} blocks for Mrntt's event loop, telling Mrntt
to shut down the Mind threads and then shut itself down.
We also split the code to initialize threads etc out of mrntt and
put it into the Mind:: namespace.
hayodea
e276fcbdce