refactoring grid lookup (step 3)

src/mol-math/geometry.ts

src/mol-math/geometry/_spec/lookup3d.spec.ts

src/mol-math/geometry/common.ts

src/mol-math/geometry/grid-lookup.ts

src/mol-math/geometry/lookup.ts

src/mol-math/geometry/lookup3d/common.ts

src/mol-math/geometry/lookup3d/grid.ts

src/mol-math/geometry/primitives/box3d.ts

src/mol-math/geometry/primitives/sphere3d.ts

src/mol-math/geometry/symmetry-operator.ts

src/mol-model/structure/model/formats/mmcif/assembly.ts

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

src/mol-model/structure/model/properties/symmetry.ts

src/mol-model/structure/model/utils/compute-bonds.ts

src/mol-model/structure/structure/element/group.ts

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

src/mol-model/structure/structure/unit.ts

src/perf-tests/lookup3d.ts