* Set parent pointers for values inserted via update() (fixes #3007).

* Moved test for #3007 to proper file.

* Enable access to private members in diagnostics unit tests.

* Make style consistent with rest of code.

* Forced amalgamate rerun.

* Refactor test for #3007 so it doesn't use private members. Also extend to test both update() functions.

* Added fix for #3007 to update(const_iterator, const_iterator) as well.

* Added failing example code from #3007 as extra test.