New Ambisonic encoder LV2

After a long time using the NON-Mixer ambisonic encoder, the difficuties to automate or control it outside of the (very good) Non-session-manager show the need to get it in a plugin.

This encoder try to port the functions of the NON-Mixer encoder to a LV2 plug-in or stand-alone application. Build with  Faust. The release work with 1st order ambisonic but it's only one constant for go to HOA.

For now we have :

- 2D & 3D Ambisonic encoding

- 2D & 3D send to a jconvolver's rev (early rev & lates)

- delay with distance

- Doppler FX with movement

- Mono or Stereo input

The config of jconvolver is the same as needed by Non-Mixer (http://non.tuxfamily.org/wiki/AmbisonicsMixing).

More detail and usage in the git repo : https://framagit.org/wargreen/ambiencoderlv2