Tour Interp Menu

This menu gives a choice of interpolation type for the tour.  The
default is geodesic interpolation, which interpolates between
planes along the shortest path.  The two additional types,
Householder and Givens interpolate between specific bases in the
planes.

For more information see "Methods for Subspace Interpolation in
Dynamic Graphics", Andreas Buja, Dianne Cook, Catherine Hurley
and Dan Asimov, submitted to JCGS.  Until it appears, information
may be requested from dcook@stat.rutgers.edu.

