Coloraide

- **FIX**: Fix `lab-d65` which was not using the correct white point in all places.

- **FIX**: Ensure that both the Bradford CAT and the XYZ transformation matrix all use ASTM E308-01 white points. This fixes a number of conversion issues when going to and from D65 to D50 color spaces.

- **NEW**: Make `mix` use the same space logic as `interpolate` and `step`. Colors are mixed in CIELAB unless `space` is set to a different color space.
- **NEW**: Add support for blend modes as specified in [Compositing and Blending Level 1][compositing-level-1].
- **NEW**: Rename `overlay` to `compose` as all compositing (including blend modes) is done through `compose` now.`overlay` is still present and is deprecated and will be removed at some future point before a stable release. `compose` will assume `sRGB` space unless a different space is specified, but `overlay` will function as it always did.
- **FIX**: Fix some small internal issues with `in_place` logic.

- **NEW**: The adjust parameter on `interpolate`, `steps`, and `mix` has been dropped. Instead, a general purpose method
has been added to the `Color` object to mask one or more channels at a time. This can be used to create a temporary
color with masked channels for the purpose of interpolation.
- **FIX**: Ensure that when `alpha` is `NaN` that it is handled in `overlay`.
- **FIX**: When using raw data in the `color()` function, and there is too little data, fill data with `NaN`.
- **FIX**: Fix issue where API `interpolate` method does not pass `out_space` parameter down.
- **FIX**: Disabling or forcing alpha did not work properly for HSL colors via `to_string`.
- **FIX**: `contrast` and `luminance` should use XYZ with a D65 white point, not the default XYZ space which uses a D50
white point.
- **FIX**: Fix bug in Delta E 2000 algorithm.