0.8.0

Added

• Set up design tokens and CSS for demo application based on Barker. Styles for
  all components will be added in the future.

Changed

General

• Add documentation for the compile-time options of the builder macros.

Property list, stack, cluster, button, and button link component

• Add styles to demo application.
• Improve story and documentation.
• Mark components as stable.

Tab navigation and disclosure button component

• Add styles to demo application.
• Improve story and documentation.
• Mark component as refining.

Icon and icon sprite component

• Add styles to demo application.
• Add story for icon sprite.
• Rename label attribute to text.
• Rename label_placement attribute to text_position.
• Change type of label_placement attribute from atom to string for
  consistency.
• Use before and after as values for text_position instead of left and
  right to better apply to right-to-left languages. Rename default classes
  to has-text-before and has-text-after accordingly.
• Make text_position classes configurable.
• Add right-to-left variation group to icon story.
• Set sprite_url as a compile time option.
• Mark both components as refining.

Date, datetime, and time component

• Improve story and documentation.
• Mark components as refining.

Fixed

• attributes for modifier variations weren't set correctly when map was
  lacking key.