chore: export Interfaces, for plugins (#968)

* Export interfaces as well (most useful for plugin framework)

Co-authored-by: Justin Litten <justinlitten77@gmail.com>

src/MusicalScore/index.ts

@@ -10,3 +10,4 @@ export * from "./VoiceData";
 export * from "./MusicSource";
 export * from "./ScoreIO";
 export * from "./Graphical";
+export * from "./Interfaces";