This reverts commit 714ef56a.

By popular demand.

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.