macosx: implemented both skipping within an item and item changing for the forward/backward buttons (closes #4943)

removed remnants of the Dudiak interface, added PXSourceList by Alex Rozanski (BSD-new licensed) which will be used for the new implementation, added a to-be-replaced png for the window's topbar

Didn't notice them first time.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

This should cleanup locking when applying the volume, though there are
still some (non-crashing) races in setting/getting the volume.

This also adds an API to report the volume from the output, though it's
currently left as a dummy.

This assumption is correct and already present in plenty of code paths
(e.g. when converting to/from float).

untested, since the affected code is part of the S/PDIF handling

Otherwise the next probed plugin would get a potentially corrupted
input format. This bug may affect other audio output plugins and
similarly even some video outptu display plugins (not checked yet).

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

New doxygen command \libvlc_return_bool means that wrapper generators
should translate returning int to a boolean value.

For example, this is useful for Ruby, where every number, including 0,
is considered to be true.

For normal HTML/LaTeX documentation it's invisible.
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

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

This prepares for a possible cleanup of the audio output object,
especially hiding more stuff into the core.

macosx: fixed updateTitle as suggested by j-b and made sure to the represented filename correctly, if applicable

macosx: remove 2 interface update timers (2 threads), 1 additional interface update thread and replaced everything by callbacks

macosx: don't use NSNotifcations to handle VLC's dialog callbacks, always perform NSAlert and friends on main thread

additionally, removed 2 clients of the manageInterface loop, which will be removed all together shortly

that's hilariously slow and CPU intensive