Extend Core Service API. Also fix #338.

New in DeepaMehtaService:
    Set<Topic> getTopics(String key, SimpleValue value, boolean fetchComposite, ClientState clientState)

Fetches topics by key and value. String values can contain wildcards like "*". Index mode dm4.core.key is required.

Furthermore (internal): instantiation traversal is fully qualified. Possible through new storage layer.
Close ticket 338.