Implement accurate CMYK color support

TODO:

• Add support for CMYK colors using the Color module for inkex 1.5
• Add a fallback for older versions

Current Behavior:

0 0.993347048759461 1 0 k

• Inkai: #ff0100, cmyk(0, 100, 100, 0)
• Illustrator: #ed2024, cmyk(0, 100, 99.33, 0)

0.929411768913269 0.662745118141174 0 0 k

• Inkai: #1155ff, cmyk(93, 67, 0, 0)
• Illustrator: #0d60ae, cmyk(92.94, 66.27, 99.33, 0)

0.533333361148834 0.980392158031464 0.474509805440903 0.545098066329956 k

• Inkai: #000000, cmyk(0, 0, 0, 100)
• Illustrator: #4e0933, cmyk(53.33, 98.04, 47.45, 54.51)