chartisan 1.2.0

Chartisan's Dart backend

[1.2.0] - Now uses double instead of int

• The dataset values now require a List<double> instead of a List<int>

[1.1.0] - Added missing method

• Fixes to the dataset() method.
• The constructor now require the ServerData instance.

[1.0.1] - Added missing method

• Added the toObject() missing method.

[1.0.0] - Initial version

• Initial release.