Creates a midi output thread using the given device, and starts it.
when the refcount reaches zero, it exits the impl thread and waits for it to join.
it refcounts the impl.
You can call any shared member of MidiOutputThreadImplementation through this struct.
This is the main feature of this module - a struct representing an automatic midi thread.
It wraps MidiOutputThreadImplementation for convenient refcounting and raii messaging.
You create this, optionally set your callbacks to filter/process events as they happen and deal with end of stream, then pass it a stream and events. The methods will give you control while the thread manages the timing and dispatching of events.