mol-data refactoring, add IntMap

src/mol-data/_spec/equiv-index.spec.ts

src/mol-data/db/column.ts

src/mol-data/db/table.ts

src/mol-data/int.ts

src/mol-data/int/map.ts

src/mol-data/util.ts

src/mol-data/util/array.ts

src/mol-data/util/chunked-array.ts

src/mol-data/util/equivalence-classes.ts

src/mol-data/util/grouping.ts

src/mol-data/util/hash-set.ts

src/mol-data/util/unique-array.ts

src/mol-io/common/binary-cif/array-encoder.ts

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

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

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

src/perf-tests/chunked-array-vs-native.ts

src/perf-tests/sets.ts