3.0 API

[dy]

@bpostlethwaite I am thinking about redesigning the API so that it looks like:

var colormap = require('colormap')

var jet = colormap('jet') //or cmap(options)
var colors = jet(72) //generate number of shades

That would allow for easier to remember API, less options and higher performance.
Also I am thinking on reducing the size, as it is addressed in #13. Due to clone dependency we include Buffer polyfill, which adds 70kb of completely useless code here.

What do you think about such major change?

Among other improvements, it is possible to optionally enable smoothstep, for enhanced color interpolation (as it is done in glsl-colormap).

[bpostlethwaite]

Love it!