v0.15.0

This release adds several new color spaces:

• A98, compatible with Adobe RGB (1998): a98
• Display P3: p3
• Rec. 2020: rec2020
• ProPhoto RGB: prophoto
• XYZ with D65 illuminant: xyz65
• JzAzBz in cartesian (jab) and polar (jch) form (#73)

Bug fixes:

• Fixes achromatic RGB to Lab conversion