This patch adds support for CoreAudio driven devices under Mac OS X. It
is typically instanciated by the CoreAudio device detection module and
handles all available streams on a specific device.
Sinks are created according to the reported stream configuration.
Float32 is used as default audio sample format at it is the only format
CoreAudio speaks natively.
Hardware volume control is not implemented yet.
This adds a new module for CoreAudio device detection. It registers a
callback to detect hotplugged devices and creates/destroys modules named
'module-coreaudio-device'. Devices are identified via a system-wide
unique AudioDeviceID.
