* Add RivSurfaceIntersectionCurveTools for shared surface intersection curve geometry
* Move the surface intersection collection to RimIntersection
* Add surface curtain footprints for the box and i/j/k intersections
* Build surface intersection curves for the box and i/j/k intersections
* Follow the pillar tilt when projecting a surface onto an intersection
* Estimate the surface intersection by continuing the pillar past the curtain