Introduce a new Chain struct that maintains the current head,
acts as facade to the store and the block processing pipeline
and handles all appropriate locking.
All higher level components, like the overall server, REST APIs
and miner have been update to only depend on Chain. Cleaned up
some duplication and tests now that there's a single entry point
to all blockchain operations.
With the coinbase receiver daemon in place, when starting a Grin
server in mining mode, the miner will now ask the receiver for a
coinbase output. The output is then used to insert in a block when
successfully mined.
Beginning of a first pass at simple wallet functionalities so
Grin can be used to author transactions. We introduce a
receiving server, to be at least able to build coinbase outputs
that can be used by the mining daemon.
Present:
* Coinbase receiving API.
* Command to start the receiving server.
* Beginning of a transaction sending command.
* Improvements to the REST API abstractions to support the above.
Still to do:
* Change to the miner daemon to use the receiving server.
* A command line sender.
* API to receive any transaction (not just coinbase).
* A command line receiver.
Beyond that, HD derivation and seed generation are very simple
so far and almost certainly insecure. Just for testing for now.
