The `begin_construction` function now accepts an optional argument
`proto_header`. This is to be used by a new RPC that ease forging the
shell header of a block (i.e. it will compute the fitness and, in a
near future, the hash of the resulting context).
This prepares the context to the inclusion the hash of the context in
the block header. By "looking" into the resulting context of a block,
we are now know able to determine whether:
- no testnet is currently associated to the branch;
- a testnet must be forked after the block;
- a previously forked testnet is running.
Intead of providing a `fitness` function, an economic protocol should
now call `Context.set_fitness`.
This simplify the shell's code and avoid complexity on protocol
change. Previously the fitness of a context produced by the old protocol
had to be read by the new protocol. Now, the shell read the context
without requesting the help of the economic protocol.
- Let the `sandbox` change the public key
- Adapt `test_basic.ml` and `test_basic.sh`
- Do not duplicate the fitness in the block header
Client:
- allow the `bootstrap` command to lookup keys in the `head` rather than
in `genesis`.
