Wrong Brightness Coefficients

https://github.com/casesandberg/react-color/blob/master/modules/tinycolor2/index.js#L76

For now there are coefficients for NTSC, not sRGB.
And i think that w3c is little bit outdated.

Also see this demo: http://codepen.io/dom1n1k/pen/LZWjbj

See sRGB table: http://www.brucelindbloom.com/index.html?WorkingSpaceInfo.html
Or point 9 here: http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html

Start at modules/tinycolor2/index.js#L76 and compare the current brightness coefficients with the linked sRGB references and demo. Confirm which coefficients are appropriate for the intended brightness calculation, then verify that the resulting behavior matches the reported sRGB expectations.

Written by the indexing model from the issue text.