* add a couple tests
* fix#4: put the whole video frame (including multiple NALs) into
a single Bytes. This is simpler to use and speeds up the
depacketize/h264_aac_writevideo benchmark. It's also a behavior
change; now I include non-VUI data such as SPS/PPS/SEI into the
data. I think this is a better default but it might be worth
making customizable.
These are huge, not present for every stream, and only allocated once at
describe time, so boxing makes sense. I probably should listen to that
clippy lint!
