sequence improvements, create sequence from coarse elements

src/apps/structure-info/model.ts

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

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

src/mol-model/sequence/sequence.ts

src/mol-model/structure/model/properties/coarse/hierarchy.ts

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

...mol-model/structure/model/properties/utils/coarse-keys.ts

src/mol-model/structure/util.ts

src/mol-plugin/ui/sequence.tsx

src/mol-plugin/ui/sequence/polymer.ts

src/mol-theme/color/entity-source.ts

src/mol-theme/color/hydrophobicity.ts

src/mol-theme/color/residue-name.ts

src/mol-theme/color/sequence-id.ts

src/mol-theme/label.ts