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.