Merge remote-tracking branch 'yargalot/master'
Merge remote-tracking branch 'yargalot/master'
Merge branch 'alpha-index'
Add methods to convert an rgba background color to rgb
Convert rgba to a solid color before checking contrast
Don't warn about rgba anymore

No need to, we are doing the maths!
Convert to a colour string

The rest of the code expects bgColour to be a string
Return rgb channels as %

Everything else expects them as %.  Also, rework to reduce rounding problems.
Allow checking against any rgba color, not just the background
Also convert the foreground (text) rgba color
Merge remote-tracking branch 'squizlabs/master' into alpha-checking
Correctly calculate layered transparencies

Take this structure of backgrounds for example, 1 being the closest element:
1. rgba(10,10,10, .5);
2. rgba(10,10,50, .1);
3. rgb(10,10,250);

We need to transform background 2 into a solid color before we transform background 1 into a solid colour.
Allow implicit labels to provide a name for input

This follows the test procedure from http://www.w3.org/TR/2014/NOTE-WCAG20-TECHS-20140408/F68
Merge remote-tracking branch 'kabel/feature-implicit-labels'