- added a "quitProc" for shutting down the p2pd process, after seeing it
survive an unhandled exception (this required a global var for the
DaemonApi instance)
- Makefile testnet0/1 targets now depend on the "p2pd" binary
- prefixed the testnet command line in the build script message with
"../../env.sh" so it can find the superproject's "p2pd"
- updated README.md
- beacon_chain.nimble: accept compilation flags as params
- nim.cfg: enable `--opt:speed` at the top level
- simulation scripts: allow overriding GIT_ROOT and do some refactoring