Allows the kernel to combine timer wakeups with other processes,
reducing power usage.

For debugging.

Use the existing PcmDither library.

Since opening the PcmVolume object can now fail, this case must be
handled.

Replaces Reset() and eliminates the AudioFormat parameters from the
Convert() method.

Wake up the OutputThread only if it hasn't already been woken up and
if it isn't already in the playback loop.

Prepare to migrate away from GLib.  Currently, we're still using GLib
as a backend.

Replaces GLib's GError.

Fixes deprecation warnings.