Removes computed test values
Adds HSV model in README
Adds supports for percent in transparentize expressions
Adds supports for opacify color function
Adds supports for saturate and desaturate functions
Adds support for grayscale function
Adds support for invert function
Adds a clampInt helper method
Adds support for adjust-hue sass function
Adds support for mix sass function

Includes:
  - the systematic use of `comma` for argument separator