account, creates an initial ledger, closes the initial ledger and opens a
new ledger, creates a second account, and adds a transaction to transfer
funds to the open ledger.
without knowledge of the objects they contain. This will allow new
transaction or account formats to be added (possibly with larger data sizes)
without breaking the ability to parse the hash trees. It also simplifies
the operation-specific tree code (since it doesn't have to parse the raw
leaf data).
