Included test case for issue#138
Added single-arg constructor option to ObjectFactoryGenerator for cases
where the destinationType has a constructor with source type as
argument.
Updated VariableRef to fix casting issue.
Added assurance of destination element instance to MultiOccurrence
mapping.
Updated debug logging on ClassMapBuilder and FieldMap to give indication
of mapping direction.
Fixed 'aggregateSpecs' portion of MapperGenerator to pay attention to
mapping direction.
Restored original ObjectFactoryGenerator code, and moved the single-arg
constructor to the 'unmatched' handler.