rose date: support more letter options

`rose date` now supports letter options for both `--*-format=FORMAT` options.

* `--parse-format=FORMAT` can now be `-p FORMAT` (for `strptime`).
* `--format=FORMAT` is now a shorthand for `--print-format=FORMAT`
  (but not `--parse-format=FORMAT`).
* `--print-format=FORMAT` can now be `-f FORMAT` (for `strftime`).

Combine `--print-format=FORMAT` and `--format=FORMAT` internally. The
effect is that `rosie lookup` and `rosie ls` will now accept
`--print-format=FORMAT`.