Operations now include a block hash in their header. Such an operation
could only be included in a successor of this block.
Furthermore, when validating a block, the economic protocol now
returns---together with the context---an integer `max_operations_ttl`.
Then, when validating a successor, the shell will fail if it contains
an operation whose header's block hash is not one the
`max_operations_ttl` predecessors of the block.
As a bonus, the shell is now able to detect and forbid replayed
operations. Then, we might decide to remove some replay
detection-mechanism that we previously implemented in the economic
protocol.
Let's get serious. The full index of operations is not sustainable in
the production code. We now only keep the index of operations not yet
in the chain (i.e. the mempool/prevalidation). Operations from the
chain are now only accesible through a block. For instance, see the
RPC:
/blocks/<hash>/proto/operations
