v1.0.0

• BREAKING: postcss-colorblind must now be used as an asynchronous plugin.
• BREAKING: Now requires PostCSS 5.
• Add support for rewriting image references where possible to color-shifted
  inline base 64 data.
• Add support for colors inside gradients.
• Fixes an issue where the whole declaration would be lowercased, destroying
  certain case-sensitive tokens. Now, only <color> values are lowercased.
• Now correctly calculates opacity for 4 & 8 character hex codes.