example: Includes 64-bit arch and targets iOS 7.
DOUAudioEventLoop: Add `-Wdeprecated`.

AudioSession related APIs have been marked as deprecated as of iOS 7, we
might switch to the higher level AVAudioSession some day in the future,
but not now.
DOUAudioVisualizer: Suppress conversion warnings.
DOUAudioPlaybackItem: Suppress a conversion warning.

Close #20.