The number of user nodes is now specified with `USER_NODES`.
To make the instructions more stable, the "numeric id" of the user
nodes will be starting from 0 (so you can always use `run_node.sh 0`
to start a user node).
If you specify a node index above the total number of nodes, you'll
launch a node without any validators attached (this is useful for
testing the sync for example).
Multi-client testing requires more portable formats, and SSZ is
much better specified than our flavour of Json.
Tools like ncli and zcli can be now used to inspect the contents
of the SSZ files.
* On the testnet site, the first N instead of the last N validators
will be considered reserved for users
* The number of validators is consistently named `totalValidators`
in all commands
* Proper keys are generated by default in validator_keygen
Zahary Karadjov
Jacek Sieka
Bruno Škvorc