A class containing utility functions for shapes.
		Note that these are all linear functions so it is neccessary to calculate separately for
		x, y (and z, w if present) components of a vector.
		
		contour -- 2D polygon. An array of THREE.Vector2()
		Calculate area of a ( 2D ) contour polygon.
		
		pts -- points defining a 2D polygon
		Note that this is a linear function so it is neccessary to calculate separately for
		x, y  components of a polygon.
		Used internally by [page:Path Path],
		[page:ExtrudeGeometry ExtrudeGeometry] and [page:ShapeGeometry ShapeGeometry].
		
		contour -- 2D polygon.
		holes -- array of holes
		Used internally by [page:ExtrudeGeometry ExtrudeGeometry] and [page:ShapeGeometry ShapeGeometry] to calculate faces in shapes with holes.
		
[link:https://github.com/mrdoob/three.js/blob/master/src/[path].js src/[path].js]