README update

Merge remote-tracking branch 'origin/NIST_DCS_2020' into NIST_DCS_2020_merge

add ability to compare firmware and software versions

int()

same

more qt compatibility..

quick and dirty workaround for PyQt incompatibility woes across versions

Update revisions.md

missing bitfile to go with last

add commit hash to revisions.md

Firmware update to protect against loss-of-clock event damaging the HV switching supply

PyQt5 stuff across versions...

Merge branch 'NIST_DCS_2020' of https://github.com/jddes/Frequency-comb-DPLL into NIST_DCS_2020

Minor cleanup, and fix one bug with configuration loading

Separate out site-specific settings for automated tests