Support for mixed digits and percentages in RGB, HSL...

[tdhsmith]

As noted in #60, ImageMagick does not allow rgb, hsl, rgba, or hsla to mix percentage and non-percentage values. (Alpha channel is excluded; it is always expected to be between 0 and 1.) This is a problem because mixing values is common (#15) and necessary. The CSS spec for HSL, for example, requires a format of hsl(<angle>, <percentage>, <percentage>).

@jbrooksuk suggested we first try to submit a patch to ImageMagick.

If that's unsuccessful or out of their scope, we'll have to add number conversion logic.

[jbrooksuk]

Marked as nobug, invalid just so we know that it's something unrelated to GC itself (for the time being).

[tdhsmith]

Submitted a bug report / feature discussion on the ImageMagick boards. Might've gone over the top on the explanation but I was procrastinating on work. :laughing:

[jbrooksuk]

Awesome! That's a really nice report, let's see where it goes!