Update `generate_makefile` to produce sensible error message in all
exceptional situations, instead of just some of them. These may surface
as one of the first things to someone getting started with the repo.
- moved "process_dashboard.nim" in "tools/"
- README: made Witti the documented testnet and added instructions for
getting metrics out of the local node
- moved Prometheus config file generation in its own script
- the static Grafana dashboard definition now covers all nodes, using
a variable; only the remote testnet dashboards need to be dynamically
generated
- "launch_local_testnet.sh" no longer needs a "--grafana" option
Etan Kissling
Ștefan Talpalaru