code: function SpotLight(name, position, direction, angle, exponent, scene) {
              var _this = _super.call(this, name, scene) || this;
              _this.position = position;
              _this.direction = direction;
              _this.angle = angle;
              _this.exponent = exponent;
              return _this;
          }
docs: Creates a SpotLight object in the scene with the passed parameters :
  - `position` (Vector3) is the initial SpotLight position,
  - `direction` (Vector3) is the initial SpotLight direction,
  - `angle` (float, in radians) is the spot light cone angle,
  - `exponent` (float) is the light decay speed with the distance from the emission spot.
  A spot light is a simply light oriented cone.
  It can cast shadows.
  Documentation : http://doc.babylonjs.com/tutorials/lights