Wall grid types

Variables
const int	Renga::GridTypes::Wall::Undefined = 0
	Undefined.
const int	Renga::GridTypes::Wall::FrontSide = 1
	Front face of a wall.
const int	Renga::GridTypes::Wall::BackSide = 2
	Back face of a wall.
const int	Renga::GridTypes::Wall::Bottom = 3
	Bottom face of a wall.
const int	Renga::GridTypes::Wall::Top = 4
	Top face of a wall.
const int	Renga::GridTypes::Wall::FirstButt = 5
	A face on the left side (when looking at the front face)
const int	Renga::GridTypes::Wall::SecondButt = 6
	A face on the right side (when looking at the front face)
const int	Renga::GridTypes::Wall::Reveal = 7
	Faces appearing as a result of insertion of an aperture.
const int	Renga::GridTypes::Wall::Cut = 8
	Faces appearing as a result of cutting a wall by other objects.

Possible grid types for a Wall mesh