Added iOS & OSX color descriptors

Added UIColor & NSColor (with rgba & hsl). It works, but this is
probably not the most optimal code - I've copied the hsl & rgb
functions and duplicated them to output the UIColor & NSColor.

This is the best I could do with my skills!
Fixed order of colours colours displayed & updated preview screenshot

Now displaying UIColor & NSColor together
Merge pull request #6 from isnav/master

Initial support for NSColor, UIColor