cleanup, array util refactoring

src/mol-data/util/interval-iterator.ts

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

src/mol-geo/representation/util.ts

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

src/mol-gl/_spec/renderer.spec.ts

src/mol-gl/renderable/util.ts

src/mol-util/array.ts