With these changes, running a simulation is very close to running
an actual testnet. Some checks have been added in the client to
make sure you are not connecting to an incompatible network (e.g.
a network running with a different number of shards).
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
Mamy André-Ratsimbazafy
Zahary Karadjov
Jacek Sieka