Currently this is just the journal and timelog file formats. This is more
scalable, but when things go wrong there is no longer just a single parse
error. For now we'll just show the first error, the one from the journal
file parser.
- get rid of undefined parse errors due to guard
- don't call error from date parsers; let add re-prompt on bad dates
- years now must always have at least four digits
- clearer date parse errors