colorGradient: generate custom linear colormaps

COLORGRADIENT allows you to generate a linear color gradient from color A to color B.

User can generate a custom linear colormap giving 2 colors and colormap depth.

Colors are given as vectors with RGB values. The suggested input method is using intensity values for each channel (0,1), but values in the (0,255) range are also allowed.

No other colorspaces are allowed (i.e. HSV,CMYK,...).

The function outputs the colormap and an image that simplify the colormap viewing process.

Use it as an alternative to colormapeditor or to generate colormaps inside your code.