feat(sleepers): the timbers of a switch get the fastenings of the rails from the submodels plate, chair and check of their model: a plate under each rail where it lies on a timber, slide chairs under the stock rails along the blades, a fastening of both where a check rail or another rail of the frog lies close beside, the legs of the nose in one plate where they're joined; the rails sit on the plate, the blades ride on the slide plates of the chairs as high as the model has them, their webs shortened; the fastenings drawn within 120 m; selftest fastenings

world/Segment.h

@@ -47,6 +47,7 @@ struct loft_span {
     loft_end toend;
     knots::line drops;
     glm::dvec2 head { 0.0 };
+    double rise { 0.0 }; // how far the foot of the profile is raised, the web below the head (head.x) shortened by as much
 };
 
 struct segment_data {