refactored ordered set

src/mol-base/_spec/collections.spec.ts

src/mol-base/_spec/ordered-set.spec.ts

src/mol-base/collections/impl/interval.ts

src/mol-base/collections/impl/ordered-set.ts

src/mol-base/collections/impl/sorted-array.ts

src/mol-base/collections/interval.ts

src/mol-base/collections/ordered-set.ts

src/mol-base/collections/ordered-set/segment-iterator.ts

src/mol-base/collections/sorted-array.ts

src/mol-data/atom-set/base.ts

src/perf-tests/sets.ts