wip, plugin interactivity

src/mol-model/structure/structure/element.ts

src/mol-plugin/behavior/dynamic/representation.ts

src/mol-plugin/behavior/static/misc.ts

src/mol-plugin/command.ts

src/mol-plugin/context.ts

src/mol-plugin/ui/sequence.tsx

src/mol-plugin/ui/viewport.tsx

src/mol-plugin/util/interactivity.ts