Ickle should be able to reference entities by unqualified name when not ambiguous

ATM, all indexed types are known in advance. There is no automatic discovery at runtime as in previous versions.

Parsing an Ickle query like "FROM org.mytests.Person" should be identical to "FROM Person" if there is a single Person type found across all packages defined in our metadata registry.

This is just a usability improvement for quick console queries and documentation should state that it is not to be used in production code as it can be easily be broken by schema updates.