The --group-by option allows for most reports to be split up into
sections based on the varying value of EXPR. For example, to see
register subtotals by payee, use:
ledger reg --group-by=payee -s
This works for separated balances too:
ledger bal --group-by=payee
Another interesting possibility is seeing a register of all the accounts
affected by a related account:
ledger reg -r --group-by=payee
The option --group-title-format can be used to add a separator bar to
the group titles. The option --no-titles can be used to drop titles
altogether.
Previously, account-wise reports used a subset of the total number of
transaction filters, but this could cause confusing results, and made
some reports immpossible (such as account-wise monthly averages).
