update atmelavr platform to 4.2.0 as 1.15.0 no longer available

fix blog link

Update ci.yml

Update the repo to more modern toolchain (#21) * Update to Espressif8266 2.6.3 toolchain This necessitates the removal (temporarily, at least) of -Werror so we can complete a compilation successfully. * Update mkdata.py for Python 3 Python 2.7 has been sunsetted since January 1, 2020. Update the builder to use Python 3.9 as it is the latest stable version. * Use GitHub Actions Since my balance went negative on Travis-CI, it has never built anything for me. Switch to GitHub Actions which works arguably better than Travis. * GitHub Actions: remove staging env The staging environment does not work, so remove it from CI for now.

only compute drift if we have at least 4 valid intervals bump version to 1.1.12

added a few comments and small debug fix

bump version to 1.1.11 print current time (GMT) with timestamps 10 samples first sample set in 4 hours

same

include pio env name in version string timestamps in samples now reflects new time and not time before offset adjustment don't include the initial first sample offset in estimated drift calculation SynchroClock version 1.1.10

improve selection of samples for drift estimate by using same criteria as for selecting offisets to use. version 1.1.9