proto: Add support for multi-channel audio and float samples

With the popularization of usage of KVM for gaming and media applications it is becoming an issue that the spice protocol does not properly allow for multi-channel audio or a higher quality sample format.

This patch adds a mapping field to the audio playback start which allows the spice server to specify the exact channel ordering of the data stream.

For higher quality audio this patch also adds the enumeration value F32 to allow for 32-bit float audio.

Signed-off-by: Geoffrey McRae geoff@hostfission.com