Resolved issue with dropping duplicate keys

[Michaelt293]

Makes duplicate keys in a YAML map a parse error.

[SamRoberts]

This seems fine, although I wouldn't be surprised if the author of moultingyaml wants the user to have the option of passing in a custom LoaderOptions to the parseYaml method.

Have you talked to the author of moultingyaml yet? I am sure he'd be happy to get this functionality merged. :)

[Michaelt293]

Thanks Sam. Yeah, I did think about whether this should be configurable. I think silently dropping data is rarely a good idea. I'm struggling to think of a situation where a user would want to drop duplicate keys. It would be nice to be able to select the behaviour you want rather than the selection being forced on you.

I haven't contacted the author, will raise a PR soon.

[Michaelt293]

Raised a PR -jcazevedo#36. I think you are right regarding the author prefering the ability to customise though. We'll see.