This leaves only synchronization code in input.c. This patch introduces
a small regression where resampling adjustment have a latency of two
packets instead of currently one. That will be fixed later.

The number of channels is conveyed in the channels mask.

The code is complete and utter crap either way.

The stream is always killed at the same time as the access already.

 - simplify "audio-filter" parser and fix a tautology
 - keep a single pointer for the resampler instead of a table

Objects cannot be detached anymore...

There should never be a need for more than 5 of them. Only the
filters proper might require more than 5 members in a chain.

The actions of the hotkeys interface all affect the playlist, the
playlist's input, the playlist's input's vout(s), the playlist's aout
or the interfaces (controller). It has no use outside VLC.

Contrary to input_GetAout(), this works even without input thread.

And remove the other instance of find-input-callback.

And get rid of the horrible find-input-callback.