Add non regression tests for this.

This solves bugs lots of RTCP spam when call params are not created appropriately.

fix AVPF management in offer-answer. Initiate an implicit avpf offer while implicit avpf is locally disabled
should result in avpf disabled locally for these payloads.

implicit avpf bugfixes: do not configure encoders to use avpf if avpf is not accepted or offered by remote.

- start ZRTP on incoming zrtp-hash even when not selected locally

- ZRTP engine is always initialised even when not selected

improve handling of legacy (buggy) opus payload type declarations: do not modify the local payload type.

-AVP implicit to AVP implicit calls now using RTCP feedback packets.
-Fixing bugs in call_tester.c

Most problematic was that declined streams were not put in SDP answers.

Do not use anymore nb_streams but SAL_MEDIA_DESCRIPTION_MAX_STREAMS and skip inactive ones because active streams won't be at the start of the array anymore

For unicast calls, continue to bind to 0.0.0.0 as we need it for multi-homed environments.