*** convert: order is reversed ?
*** convert: clean up default rules file
*** convert: use default rules when converting stdin with no --rules
*** convert: consistent multi-field formats allowed for any field
*** convert: optionally generate single-entry txns
*** convert: optionally set final amount blank
*** convert: parse HH:MM[:SS] as an amount, converting to decimal hours
*** convert: ignore heading row
*** convert: warn and ignore unparsed rows ?