Add ability to only use lego colors

[JuanPotato]

Putting this here for conversation and progress

[stuaxo]

You could extract the colors from the ldraw parts library.

[Haroenv]

Good idea!

[mattdbr]

Here's a list of in use, transparent and phased out colours: http://lego.wikia.com/wiki/Colour_Palette

[wentz-s]

http://www.bricksfinder.de/lego-shop-color-list/

Just found this, maybe it will be helpful.

[RealJTG]

LEGO releases its internal color palette (2010)
LEGO colors limeline (3450x7619!) (© Brick Colorstream)
Also http://www.peeron.com/cgi-bin/invcgis/colorguide.cgi

Not a big deal actually if we make legofy to accept any png image as reference palette. I suggest you to start from here: http://pillow.readthedocs.org/en/3.0.x/_modules/PIL/Image.html#Image.quantize

[JuanPotato]

well, done, forgot to mention in commit