wip, improved marking and picking

src/apps/canvas/component/structure-representation.tsx

src/apps/canvas/component/viewport.tsx

src/apps/canvas/structure-view.ts

src/apps/viewer/index.tsx

src/mol-app/ui/visualization/viewport.tsx

src/mol-geo/representation/index.ts

src/mol-geo/representation/shape/index.ts

...ol-geo/representation/structure/complex-representation.ts

src/mol-geo/representation/structure/complex-visual.ts

...l-geo/representation/structure/representation/backbone.ts

...representation/structure/representation/ball-and-stick.ts

...o/representation/structure/representation/carbohydrate.ts

...ol-geo/representation/structure/representation/cartoon.ts

...esentation/structure/representation/distance-restraint.ts

src/mol-geo/representation/structure/representation/point.ts

...-geo/representation/structure/representation/spacefill.ts

src/mol-geo/representation/structure/units-representation.ts

src/mol-geo/representation/structure/units-visual.ts

src/mol-geo/representation/structure/visual/element-point.ts

...ol-geo/representation/structure/visual/util/nucleotide.ts