Pywaggle

Improve accuracy of Camera image timestamps by time stamping between frame grab and decode steps.

Contributed by gemblerz.

This release drops support for publishing bytes values via Plugin.publish.

Though this was technically allowed by pywaggle before, the node data pipeline would silently drop messages with bytes data leading to confusion on for the end user.

In the future, we may change our position on this but our current recommendation is to either:
1. Unpack binary data into individual int, float or string fields.
2. Manage your own serialization and deserialization scheme.

This release updates the run log `data.ndjson` format to be compatible with the data API and [sage-data-client](https://pypi.org/project/sage-data-client/)'s load function.

This should reduce tooling friction when transitioning from development to deployment of apps.

Graduated run log directory out of alpha and added [usage documentation](https://github.com/waggle-sensor/pywaggle/blob/main/docs/writing-a-plugin.md#6-access-run-logs-optional) to docs.

Initial alpha test of pywaggle log directory support!

If the environment variable `PYWAGGLE_LOG_DIR=path/to/dir` is defined, then pywaggle will publish measurements and uploads to `path/to/dir` as plain files in the following format:

txt
path/to/dir/
data.ndjson
uploads/
nstimestamp1-filename1
nstimestamp2-filename2
...


Messages are currently logged in `data.ndjson` in the following "raw", line separated JSON format:
json
{"name":"env.temperature","ts":1656449073603869000,"meta":{"sensor":"bme280"},"val":23.0}
{"name":"upload","ts":1656449073603976000,"meta":{"camera":"top","filename":"test.png.webp"},"val":"/Users/sean/git/pywaggle-log-dir-example/testrun/uploads/1656449073603976000-test.png.webp"}
{"name":"image.cats","ts":1656449074613277000,"meta":{},"val":0}
{"name":"image.birds","ts":1656449074613507000,"meta":{"camera":"left"},"val":8}
{"name":"timeit.inference","ts":1656449074613580000,"meta":{},"val":1005408000}


The log is flushed for each measurement, so piping the log and commands like `tail -f path/to/dir/data.ndjson` work as expected.

Bug fix: Actually fixed subscribe. (Fixed internal queue passed to consumer.)