Support CSS3/X11 color names

The current set of color names is determined by the Java AWT color names, which are basically the base 16 colors, plus a few. The latest web standards build in the X11 colors names, which are a much larger list (see https://en.wikipedia.org/wiki/X11_color_names, and note the differences between CSS3 and X11).
I would propose implementing the W3C standards since these are what current web applications will be using.
The changes are easy enough (except for the "gray" vs. "grey" spellings and possibly the X11/CSS3 differences) that I would consider changing it for 2.0.5 except that this is a spec change that doesn't belong in a bug fix release (unless someone could make a good case for it).