FS-11785 [mod_conference] Fix dead assignments.  Removed auto-record-canvas-id param which never did anything.

                          fix dead assignments in conference_cdr

               null attribute in esl_buffer_read
	       null attribute in esl_event_base_add_header
	       null attribute in esl_recv_event

FS-11785 [mod_commands] scan-build thinks NULL parameter is being passed to function.  Shouldn't actually happen.

FS-11785 [mod_av] fix a couple dead assignments and inconsistent assumption that mm pointer could be NULL

FS-11784 [mod_sofia] quiet the codec negotiation error log.  It's something that is not necessarily a FS issue.

FS-11713: [core] fix a calls b with video, b answers with audio and then turns on video (A will have to unpause video too)