- 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
To enable it, comment out the 'withLibp2p' line in nim.cfg
The history was squashed in order to remove an accidentally
commited binary file.
Other changes:
* SSZ was adapted to use the common serialization framework
* gossibsup.subscribe is not using async handlers at the moment
and this allowed me to simplify it