function vert( x, y, z ) {

		return scope.vertices.push( new THREE.Vector3( x, y, z ) ) - 1;

	}
@author WestLangley / https://github.com/WestLangley
@author zz85 / https://github.com/zz85
@author miningold / https://github.com/miningold
@author jonobr1 / https://github.com/jonobr1

Modified from the TorusKnotGeometry by @oosmoxiecode

Creates a tube which extrudes along a 3d spline

Uses parallel transport frames as described in
http://www.cs.indiana.edu/pub/techreports/TR425.pdf