macosx: icon set for the sidebar table taken from the Fogue icon set by Yusuke Kamiyamane, licensed as Creative Commons Attribution 3.0 unported (CC BY 3.0)

note: playlist view isn't connected to the side bar yet

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

Also prefix with vlc_ for namespace cleanliness.

If a non-default UDP multicast destination port is used, it can and
should be specified through the MRL. Anyway, you should not use raw UDP
streaming ;-)

macosx: fixed volume slider appearance in black intf mode and disable the track slider when appropriate

Audio output plugins can use this to expedite discarding pending
buffers. This reduces latency upon seeking or stopping the input.

This new callback also supports explicit draining, but this is not
used for the time being.