Update colors names to match Web Colors standard

While checking the colors of Taurus for a sardana issue, I realized that some of the colors names don't follow any standard (at least any standard I could find).
This MR changes the color names to match Web Colors, an easy global standard. In fact, HTML and CSS actually use the names, so someone needs to use Taurus Colors in web, it's as simple as writing "color:name" (without needing to write the rgb or hex codes).
A couple of the Taurus Colors didn't match any web color, so I'm adding "Taurus -" at the start of the name to indicate that is a custom color. Those 2 colors are now named "Taurus - x", where x is the name of the most similar color in Web Colors.