Make the core library available separately from its dependencies

[bipster]

Whether a project is Maven-based or not, the json.org code might be a surprise since it's baked into the Semantics3 project itself and not referenced in the pom.xml. This complicates projects that already use json.org code, because if which version gets class-loaded first could differ from JVM to JVM and the runtime errors could seem nondeterministic/confusing.

Providing a "thin" JAR with the core Sem3 code and explicitly listing the json.org version brought into the project could help.