* add changes to use chronos v4 in compat mode
* switch chronos to compat fix branch
* use nimbus-build-system with configurable Nim repo
* add missing imports
* add missing await
* bump compat
* pin nim version in Makefile
* add await instead of asyncSpawn to advertisement queue loop
* bump DHT to v0.5.0
* allow error state of `onBatch` to propagate upwards in test code
* pin Nim compiler commit to avoid fetching stale branch
* make CI build against branch head instead of merge
* fix handling of return values in testslotqueue