v1.0.0

• Added toIso method which returns ISO 8601 Duration format from the IsoDuration object.
• Added withDate method which adds/subtracts IsoDuration from a DateTime

final isoDur = IsoDuration.parse('PT12H');
final dateTime = DateTime(2021, 1, 20, 8); // 2021-01-20 08:00:00.000
isoDur.withDate(dateTime); // 2021-01-20 20:00:00.000

• Added format method which formats IsoDuration to specified String format

final durFormat = IsoDuration.parse('PT4H5M');
durFormat.format('See you in {hh}h {m}m'); // See you in 04h 5m

• Other added methods: isAfter, isBefore, isAtSameMomentAs, isPrecise, hasDecimals, copyWith
• Added a possibility to parse negative durations. Minus operator is allowed only before the literal P. An example:

-P1DT15H

• Bug fixes.
• Updated dependencies.