Window grid types

Variables
const int	Renga::GridTypes::Window::Undefined = 0
	Undefined.
const int	Renga::GridTypes::Window::Frame = 1
	Faces of a frame.
const int	Renga::GridTypes::Window::Glass = 2
	Faces of a glass pane.
const int	Renga::GridTypes::Window::Sill = 3
	Faces of a sill.
const int	Renga::GridTypes::Window::OutwardSill = 4
	Faces of an outward sill.
const int	Renga::GridTypes::Window::Reveal = 5
	Faces of a wall appearing as a result of a window insertion.

Possible grid types for a Window mesh