REL-2059: Fix faulty comparison of enum options in Obs objects.

This is a fix I need to get some other (unrelated) tests working I was originally working on.. Side effects on QPT should be minimal because options are mainly used for informational purposes (displayed as properties for the selected observation). This is probably also the reason why nobody noticed this.
I guess I was wondering whether the code for the null/null case at the top should also be used for the last case where both are not null and the ordering is the same.  If we did that, the only difference I can see is that it would handle/cover up the case in which two different enums have the same order.  If two different enums are not supposed to have the same order and if this will make it fail every time then the way you wrote it is obviously better though.  The relationship with the `ORDER` map is a bit tricky but I don't know what else to suggest. :+1: