Add kitspace.yml for revC1. See https://kitspace.org/ for details.

applet.sensor.bmx280: add humidity measurement support, on BME280.

applet.sensor.{bmp280→bmx280}: add BME280 support. This is just for temperature and pressure, no humidity measurement yet.

applet.sensor.hx711: fix accession number.

applet.radio.nrf24l01: fix typo.

software: drop Python 3.6 support (for real this time). This was done about half a year ago and then reverted in b5c7f127 by popular request. The main reason to migrate is the proper support for required subparser arguments in argparse, the lack of which caused rather frustrating incidents: forgetting to specify a command would silently do nothing, which without verbose logging enabled can look identical to a command executing successfully.

applet.sensor.hx711: add configurable frequency source. This frequency source can drive the XI pin to allow a wider range for and more accuracy of the sample rate.

support.data_logger: always timestamp InfluxDB requests. To avoid missing data points when batching. This still relies on the system clock being high resoltion and could still result in missing data points. In principle there is no way to avoid missing data points completely (the user can specify lower precision than the sample rate), and while we could fudge timestamps in case we detect a low resolution system clock, that is almost certainly worse than just dropping those points entirely.

support.data_logger: fix explicitly specified timestamp for InfluxDB.

support.data_logger: queue and batch data for InfluxDB. This results in much higher performance, allowing the use of ~100 Hz sample rate sensors than ~1 Hz rate. As a side effect, this feature also resubmits data that would previously be lost due to network errors. This may cause the queue to grow without bounds though.