Colormap solarized for level intensity

solarized(m) returns an mx3 color map of level intensity.

In color graphics the colormaps often have very varied intensity which makes visualisation hard. For example, the usual green, yellow and cyan are hard to see. The solarized colormap function provides colors with a much more even intensity for easier viewing. Implements a color map from the eight colors at http://ethanschoonover.com/solarized The colormap is by linear interpolation if m>8, or subsampling if m<=8.