code: function( x, y, z ){
  			if( hasXYZ( x ) ){
  				//it was 1 param, it was a vector or object
  				this.vertices.push( new Vec3D(x) );
  			} else {
  				this.vertices.push( new Vec3D(x,y,z) );
  			}
  			return this;
  		}
docs: add a vector to the line-strip, it will always be a copy
  @param {Vec3D | Number } x either a Vec3D or an x coordinate
  @param {Number} [y]
  @param {Number} [z]
  @return itself