basic support for models from cif-core files

data/cif-field-names/cif-core-field-names.csv

src/mol-io/reader/cif/schema/cif-core.ts

src/mol-model-formats/structure/cif-core.ts

src/mol-plugin-state/actions/data-format.ts

src/mol-plugin-state/actions/structure.ts

src/mol-plugin-state/formats/registry.ts

src/mol-plugin-state/formats/trajectory.ts

src/mol-plugin-state/transforms/model.ts

src/mol-plugin/index.ts