If we receive a currentChanged, and currentView ain't set, we might crash in
handleExpansion

Crashes have happened at
StandardPLPanel::handleExpansion (this=<value optimized out>, index=@0x406b56a0) at
components/playlist/standardpanel.cpp

Spotted by jpeg.

And adapt the actions in consequences

Returns a direct pointer to the extensions_manager_t

We need to actually delete the sinks for incoming connections...

It could be used to update the netsynch module or to lock the input
clock on the audio one.

Partially based on a patch by Jean-Paul Saman.

Original patch by Jean-Paul Saman.

This saves one unlock/lock cycle, and makes sure that the reparented
object remains in the tree at all times. This does not fix the race in
reparenting, but it reduces its window of opportunity.

This also makes vlc_object_detach() essentially redumdant with
vlc_object_release() and vlc_object_attach().