Added ComputerCraft colours

Still to add

[Colours Combine](http://computercraft.info/wiki/Colors.combine) *note:* vararg function
[Colours Subtract](http://computercraft.info/wiki/Colors.subtract) *note:* vararg function
[Colours Test](http://computercraft.info/wiki/Colors.test) *note:* needs to accept this colour block as well as number blocks since a colour is just a number between 2^0 and 2^15

[Colours API](http://computercraft.info/wiki/Colors_(API))