Add output-mixed-per-media

[dvillaume]

This should allow mix outpout per media instead of per flow.

One advantage is to identify caller an callee in case of siprec with dual media :

m=audio 41828 RTP/AVP 8 9 0 101 a=rtpmap:9 G722/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:0 PCMU/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-15 a=ptime:20 a=sendonly a=label:1 m=audio 41830 RTP/AVP 8 9 0 101 a=rtpmap:9 G722/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:0 PCMU/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-15 a=ptime:20 a=sendonly a=label:2

My dev's skills are limited so i'm opened to any remark.

[rfuchs]

Let me know when this is ready for review

[dvillaume]

Hello, i pushed a new version using the media session ordered in the sdp to be sure to keep the orgiginal order. Do you think you could have a look ?

[dvillaume]

Hello @rfuchs, Do you think this could be merged ? Thanks

[rfuchs]

It just got merged now