This picks up moonfire-ffmpeg's 4b13378:
support ffmpeg's multi-call log messages
This should fix this annoying log output:
```
W20210310 13:17:09.060 s-garage_west-main moonfire_ffmpeg::rtsp] 0xaf300950: RTP H.264 NAL unit type 29
W20210310 13:17:09.060 s-garage_west-main moonfire_ffmpeg::rtsp] 0xaf300950: is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
```
so it looks like this instead:
```
W20210310 13:17:09.060 s-garage_west-main moonfire_ffmpeg::rtsp] 0xaf300950: RTP H.264 NAL unit type 29 is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
```
* add more description to the troubleshooting guide
* adjust the log format to match more recent glog
* include a config for the lnav tool, which will help colorize,
browse, and search the logs.
Next up: install an ffmpeg log callback for consistency.
This was mostly straightforward. The most confusing part waas the Sync
bound change on body streams. I copied what hyper did and it seemed to
work. /shruggie
Besides being more clear about what belongs to which, this helps with
docker caching. The server and ui parts are only rebuilt when their
respective subdirectories change.
Extend this a bit further by making the webpack build not depend on
the target architecture. And adding cache dirs so parts of the server
and ui build process can be reused when layer-wide caching fails.
Scott Lamb