generic loci support for overpaint, substance, clipping

CHANGELOG.md

src/mol-plugin-state/helpers/structure-clipping.ts

src/mol-plugin-state/helpers/structure-overpaint.ts

src/mol-plugin-state/helpers/structure-substance.ts

src/mol-theme/clipping.ts

src/mol-theme/overpaint.ts

src/mol-theme/substance.ts