Adm renderer (fixup)

[tguillem]

Based on #23

Just reworking commits messages and order, and fixing few warnings.

[kwizart]

Fixed a bug that caused an allocation error

This commit breaks API with vlc-3.x
Is there a way to avoid the API break ?

audio_filter/channel_mixer/spatialaudio.cpp: In function 'int Open(vlc_object_t*)':
audio_filter/channel_mixer/spatialaudio.cpp:512:33: error: no matching function for call to 'CAmbisonicZoomer::Configure(unsigned int&, bool, int)'
  512 |     if (!p_sys->zoomer.Configure(p_sys->i_order, true, 0))
      |          ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/spatialaudio/AmbisonicProcessor.h:22,
                 from /usr/include/spatialaudio/Ambisonics.h:28,
                 from audio_filter/channel_mixer/spatialaudio.cpp:43:
/usr/include/spatialaudio/AmbisonicZoomer.h:40:18: note: candidate: 'virtual bool CAmbisonicZoomer::Configure(unsigned int, bool, unsigned int, unsigned int)'
   40 |     virtual bool Configure(unsigned nOrder, bool b3D, unsigned nBlockSize, unsigned nMisc);
      |                  ^~~~~~~~~
/usr/include/spatialaudio/AmbisonicZoomer.h:40:18: note:   candidate expects 4 arguments, 3 provided
make[4]: *** [Makefile:26640: audio_filter/channel_mixer/libspatialaudio_plugin_la-spatialaudio.lo] Error 1