Will take some experimentation to see if this is what I want the API
to be, if the memory usage is acceptable, etc.
This will force a total reindex for wizards-wallet users.
[breaking-change]
Turns out TOML does not support tables named "", so we instead encode
the accounts list as an array rather than a name-keyed hashmap. This
is fine since the account name is in the account structure itself
anyway.
Andrew Poelstra