philipel f472c5b672 Implement the NackModule as part of the new jitter buffer.
Things done/implemented in this CL:
  - An interface that can send Nack (VCMNackSender).
  - An interface that can request KeyFrames (VCMKeyFrameRequestSender).
  - The nack module (NackModule).
  - A set of convenience functions for modular numbers (mod_ops.h).

BUG=webrtc:5514

Review URL: https://codereview.webrtc.org/1715673002

Cr-Commit-Position: refs/heads/master@{#11882}
2016-03-05 11:56:45 +00:00
..
2015-12-16 19:44:39 +00:00