Add support for linear and radial gradients

[andymeneely]

Would be nice if we could do gradients instead of fill colors for background and the various shapes. Cairo supports multiple stops, which makes them quite variable

Here are the examples/ideas:

background gradient: { x1: 0, y1:0, 
                       x2: 500, y2: 500, 
                       colors: {0.0: :red, 
                                1.0: :blue }
                     }

It would be the first time we would have the inputs be hashes within hashes (within hashes). Is that too complex? Is there another way?

Or... do we just say "use SVG". Perhaps that would keep things simpler.

[andymeneely]

Or perhaps translate colors? That would make the syntax easier I think. Everywhere colors are specified, you can specify gradients too. Maybe accept the hash syntax, but also a more natural string syntax. Such as:

"(x1,y1) (x2,y2) blue [0.1] #abc [1.0]"

[scraimer]

Either option sounds good, although I suspect that the hashes-within-hashes might conform better to how you've been implementing the deck: that is, that everything is arrays and each item in the array is used in a single card.

The string method is probably less convoluted to use, though.

[andymeneely]

I went with just the string formatting. Mult-level hashes complicate things more than I want to deal with at this point. It'll be in the next release.