wip, carbohydrates orientation

...presentation/structure/visual/carbohydrate-symbol-mesh.ts

src/mol-math/linear-algebra/3d/vec3.ts

src/mol-model/structure/structure/carbohydrates/compute.ts

src/mol-model/structure/structure/carbohydrates/constants.ts

src/mol-model/structure/util.ts

src/mol-view/stage.ts