New !COLOUR finish

[Travis Cobbs]

I think I'm ok with leaving this to the part editors / library maintainer

So I'm ok with the MATERIAL variants.

Are we going to define the parameters too?

I think we should list the known types, which I think right now are:

• <none> (standard minifig cape material)
  
• VELVET
  
• FUR
  
• CANVAS
  
• STRING