The default low-latency buffer size is now 10 milliseconds per period.
The default conservative buffer size is now 100 milliseconds per
period.

This simplifies the callback since the client does not need to worry
about silencing parts of the buffer that are not filled, such as the
end of a song or whatnot.

The change this commit is reverting causes glitching with smaller
buffers for some reason. More investigation into this is required.

Playback-only and capture-only modes are broken with this commit.

This commit also experiments with a fix for glitching in full-duplex
mode.

Playback-only and capture-only modes are broken with this commit for
DirectSound.

Fix vorbis playback

This fixes a bug where the wrong position is being retrieved for the
capture device.

This change makes it so reading and writing is done on the smaller of
the period sizes between capture and playback devices.

The new rule is to start playback when the entire buffer is filled
rather than when the first period is filled in duplex mode. Normal
playback mode will still start the device when the first period is
filled.

This commit attempts to address a crackling issue in full-duplex mode.

* When the capture buffer becomes over-filled it will discard some
  frames to prevent it from straddling the capacity of the internal
  buffer and causing excessive overruns.
* A fix has been implemented to the function that retrieves the number
  of available frames in the device's internal buffer.
* Low-latency shared mode (IAudioClient3) forces small buffer sizes so
  a change has been implemented which bypasses low-latency shared mode
  when a large buffer is specified.