pd9333

Allow using digits in `--base` flag.

Close #7 See detailed description in #7

Minutes of negative offset also need multiplier

5

Code here: https://github.com/rtfeldman/elm-iso8601-date-strings/blob/3587ff12251261514d0da49837f3c170d0249448/src/Iso8601.elm#L342-L345 Might be: ```elm multiplier * (hours * 60 + minutes) ```