You can now write both @/@@ costs and corresponding equity conversion postings
in a transaction at any time, not just when using --infer-costs or --infer-equity.
hledger will recognise the redundancy and ignore it.
One thing has become more strict: hledger now requires conversion postings
to occur in adjacent pairs; an odd number of them is not allowed.
(Conversion postings are postings to accounts of type `V`/`Conversion`,
or named `equity:conversion`, `equity:trade`, `equity:trading`,
or subaccounts of these.)
And, --infer-costs now works in transactions with an implicit amount
(inferring costs from equity now happens after transaction balancing,
not before).
This requires checking parent accounts for any new accounts introduced by auto postings which do not exist in the original journal.
Also refactor journalFinalise to only call journalPostingsAddAccountTags once, and use fewer intermediate variables.
