added gap visual

src/mol-data/int/sorted-ranges.ts

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

...o/representation/structure/visual/polymer-gap-cylinder.ts

src/mol-geo/representation/structure/visual/util/polymer.ts

...l-model/structure/model/properties/utils/atomic-ranges.ts

...l-model/structure/model/properties/utils/coarse-ranges.ts

src/mol-view/stage.ts