ability to set arbitrary PulseAudio properties

It would be very helpful if one were able to set arbitrary PulseAudio properties through libvlc (e.g. being able to apply a map<string, string>).

Rationale being that PulseAudio supports a vast array of properties that couldn't possible all be expressed through generic libvlc API like app_id yet an application may want to set them. For example a binary blob application icon.