Add documentation and sample output for `--commodity-column` behavior
and functional tests e.g single-period balance, yearly balance, and
yearly budget
This adds the `--commodity-column` option that displays each commodity
on a separate line and the commodities themselves as a separate column.
The initial design considerations are at
simonmichael.hledger.issues.1559
The single-period balance report with `--commodity-column` does not
interoperate with custom formats.
