WS/MP4 reliability edits:

- Stream selecting now obeys new "maxdelay" capa entry
- Output::liveSeek now takes an optional bool argument to indicate only rate control should be applied (no seeking)
- dataWaitTimeout is now configurable per-output, defaults to the old 25s
- WS/MP4 uses the new liveSeek with rate-control only
- WS/MP4 uses the new dataWaitTimeout and sets it to 4.5s
- WS/MP4 uses the new maxdelay capa, sets it to 5s
- WS/MP4 will now auto-reselect tracks if a track is dropped for data wait timeout or disappeared from metadata reasons
- Added support for jitter information in WS/MP4 protocol
- Robustify sendWebsocketCodecData being ran when sendHeader is ran
- Fix race condition when switching video tracks before previous video track has sent a single frame

src/output/output_mp4.h

@@ -108,7 +108,9 @@ namespace Mist{
     void onWebsocketFrame();
     void onIdle();
     virtual bool onFinish();
+    virtual void dropTrack(size_t trackId, const std::string &reason, bool probablyBad = true);
   protected:
+    bool possiblyReselectTracks(uint64_t seekTarget);
     void sendWebsocketCodecData(const std::string& type);
     bool handleWebsocketSeek(JSON::Value& command);
     bool handleWebsocketSetSpeed(JSON::Value& command);