Threading: run all code in PThreads, add JOLTing & exception bubbling

This commit significantly restructures the way we setup threading in
SMO. We now don't use the CRT main() thread at all. It's only used
as a mechanism to ensure that Marionette doesn't execute before
global constructors have been executed.

JOLTing:

This is a simple ASIO post()ed message that makes each thread setup
its thread-local data pointer to its own ComponentThread object,
and then enter its main ASIO run() loop to await commands from
Marionette.

Exception bubbling:

We now cleanly cause mind threads to report their exceptions
to marionette, so that marionette can cleanly shut the mind down
in an orderly fashion.

Thread Control messaging API:

A namespace of asynchronous messages to be post()ed to threads to
control them. It enables us to pause and resume threads. This will
be very useful for Marionette when we add the ability for it to
suspend Salmanoff's running mind, inject new goals, inspect current
state, etc; and then resume the mind's execution.

smocore/CMakeLists.txt

@@ -9,6 +9,6 @@ target_include_directories(smocore PUBLIC
     ${CMAKE_CURRENT_SOURCE_DIR}/include
 )
 
+add_subdirectory(marionette)
 add_subdirectory(deviceManager)
 add_subdirectory(senseApis)
-add_subdirectory(marionette)