moving GraphPathInfo into relationships-api and doing away with the stateful, impl-specific versions. Also, making GraphView, GraphWorkspace, GraphPathInfo, ProjectRelationshipFilter, and GraphMutator serializable so we can cache them in the graph to make tracking of membership in a view less expensive. Started working on view-membership tracking in neo4j driver, but I still need to hook it up to the getAll*() methods and determine how eagerly to explore view membership when a new relationship links a view into a whole pre-existing subgraph.