colour lib needs reviewers

[Basile B. via Digitalmars-d]

On Monday, 12 September 2016 at 04:14:27 UTC, Manu wrote:
> I think I'm about as happy with my colour lib as I'm going to 
> be. It really needs reviews.
>
> I'm not sure what else should be in the scope of this lib.
>
> PR: https://github.com/dlang/phobos/pull/2845
> dub: https://code.dlang.org/packages/color
> docs: 
> http://dtest.thecybershadow.net/artifact/website-04a64e024cf75be39700bebd3a50d26f6c7bd163-7185c8ec7b15c9e785880cab6d512e6f/web/library-prerelease/std/experimental/color.html
>
> [...]
> - Manu

1. Maybe that the each package ddoc comment should mention that 
everything is always @safe nothrow @nogc...For me it wasn't 
directly clear:
- seen that there's opCast: Q: safe ?
- seen in the sources that opCast call a templatized function
- seen that the unittest for this function are not annotated
- then only seen that the leading "@safe nothrow @nogc:" at the 
beg of the package.

2. Q: is there anything to convert a color to grey scale ?