colormaps

Provides basic tools for colormap creation using the method by Wijffelaars, M. et al. 2008.

Most simple usage is by defining the hue of the map (in LCHuv)
```julia
colormap(250)
```
![hue_examp](https://f.cloud.github.com/assets/3612029/1646915/e3efc282-592b-11e3-9c32-f0c6e7adf098.png)

or by giving the name of the color
```julia
colormap("Reds")
```
![hue_examp2](https://f.cloud.github.com/assets/3612029/1646920/1d41a8ca-592c-11e3-82af-23172fd8c685.png)

In addition, one can easily change the number of colors in the palette
```julia
colormap("Greens", 10)
```
![hue_examp3](https://f.cloud.github.com/assets/3612029/1646933/82f32e6e-592c-11e3-9702-17646b923a79.png)