Adding (or modifing) color.

[nsanmartin]

In some terminals the blue color for characters with black background is hard to read. This happens to be the default color for the anchor elements. Although we can change that in the options, there are not so many options (8 in total), and if I substitute it for, say, cyan, for example, then I'll have to change the "Color of mark" to blue again to distinguish.

Is there a way to add a new color to the set of options or to replace one (or more) of the existent ones?