Dropping XP and Vista support

[Austin Hicks]

Pretty much the subject. I've been intending to kill the WaveOut
backend forever; it's gone. I'm not going to invest the time to rewrite
it almost from scratch.


Vista is going to limp along for a while because there are not
significant differences between Vista and 7 in terms of the audio API.
Unless there's popular demand, though, i'm going to kill it if one of
them comes up, and I'm not going to go out of my way to fix
Vista-specific bugs. If I recall, this is likely to arise when we get
microphones because Vista doesn't support event-driven streams for
microphones unless you've got SP1.