* re-enable setting for enabling/disabling rtx
* add tests for rtxmodifier. (and a bugfix found by the tests)
* remove rtx handling from sdp-consistency (it will be handled separately)
* better error printing in JingleSessionPC around renegotiation
* add rtx modifier to handle inserting local rtx ssrcs, keeping local rtx ssrcs consistent, and imploding remote rtx ssrcs
* jsdoc, es6 cleanup, logging tweaks
* fix line that's too long
* add a 'parseGroupSsrcs' helper function
* fix a bug when passing group ssrcs to be parsed
* address pr feedback
* address pr feedback
* fix for loop
* address pr feedback
* better const in SampleSdpStrings
brian baldino