Working with doubles as string is wrong

[avioli]

https://github.com/MikeMitterer/dart-latlong/blob/0325c7d911b620c4f7efe9c9136a20ea7730c837/lib/latlong.dart#L92-L111

When dec is 53.0335 then splitting a double into two parts, that then get parsed as integers is wrong!

The fractionalPart 0335 becomes an integer - 335, and then "recreating" a double by doing 0.$fractionalPart is simply silly.

0.335 != 0.0335

final String sexa2 = decimal2sexagesimal(-42.883891);
expect(sexa2, '42° 53\' 02.01"'); // got '42° 53\' 20.08"'

The right way of doing this is:

/// Converts a decimal coordinate value to sexagesimal format
///
///     final String sexa1 = decimal2sexagesimal(51.519475);
///     expect(sexa1, '51° 31\' 10.11"');
///
///     final String sexa2 = decimal2sexagesimal(-42.883891);
///     expect(sexa2, '42° 53\' 02.01"');
///
String decimal2sexagesimal(final double dec) {
  if (dec == null) throw new ArgumentError.notNull('dec');

  final buf = new StringBuffer();

  final double absDec = dec.abs();
  final int deg = absDec.floor();
  buf.write(deg.toString() + '°');

  final double mins = (absDec - deg) * 60.0;
  final int min = mins.round();
  buf.write(' ' + zeroPad(min) + "'");

  final double secs = (mins - mins.floorToDouble()) * 60.0;
  final int sec = secs.round();
  final int frac = ((secs - secs.floorToDouble()) * 100.0).round();
  buf.write(' ' + zeroPad(sec) + '.' + zeroPad(frac) + '"');

  return buf.toString();
}

/// Pads a number with a single zero, if it is less than 10
String zeroPad(num number) => (number < 10 ? '0' : '') + number.toString();

Sorry, I'm calling this function a lot, so StringBuffer makes sense for me.