DATACMNS-580 - Add section on limiting the query results to reference documentation.

Added section explaining the use of first / top keywords to the reference doc.

Original pull request: #99.
DATACMNS-583 - DomainClassConverter returns input if given types are the same.

DomainClassConverter now returns input when the source type is identical to the target type. Previously we erroneously tried to convert the sourceType to the idType of the targetType's backing repository. As a side effect we also avoid performing some unnecessary converter hops.

Original pull request: #101.