wip, picking location and label

src/mol-geo/representation/index.ts

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

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

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

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

src/mol-geo/representation/volume/surface.ts

src/mol-geo/util/color-data.ts

src/mol-geo/util/picking.ts

src/mol-view/viewer.ts