- Classes submitted as result_class for a resultsource are now
automatically loaded via ensure_loaded()
- 'result_class' resultset attribute, identical to result_class()
- - add 'null_on_fk' option for relationship accessors of type 'single'.
+ - add 'undef_on_null_fk' option for relationship accessors of type 'single'.
This will prevent DBIC from querying the database if one or more of
the key columns IS NULL. Tests + docs (groditi)
- for 'belongs_to' rels, 'null_on_fk' defaults to true.