... Should have no effect on generated code, except perhaps some slight faster
virtual function calls. Mostly useful as documentation of design intent.
Tried to mark every one of our classes that inherits from another, or is a
base for others, or has abstract virtual functions, and a few others besides.
I say possible because I can't fully test it as my motherboard
audio device doesn't show up in Windows (don't know why yet).
So, because of that and because this "fix" needs a little discussion
amongst the troops, I've ifdef'd it with EXPERIMENTAL_HAVE_DEVICE_CHANGE
and have disabled it by default.
What is does is it sets up a device change listener and performs an
automatic rescan when a change is detected. (That's the part that
needs discussion.)
