Use ParaView's cylinder widget to model cylinders in SMTK.

There is now an infinite-cylinder widget, which can be bound to a Group item containing 3 Double children that serve as a center point, a direction vector, and a radius. Note that the widget models a cylinder of infinite length cut by a bounding box whose size is not currently specified.

Also, there is a cone-widget which can be bound to a Group item containing 4 Double children that serve and endpoints and endpoint radii. As a special case, it can also be requested to act as a finite cylinder in which case only a single radius is used.