Inverse transformer introspection

[rafaelnobrepd]

This should close #1949 , I had the same issue and was upset for not being able to register a custom transformer globally because of the documented lack of ability to infer types on inverse mappings (because of NSMutableDictionary objectClass)
The implementation is roughly the same as #2095 , only during the inverse mapping construction, introspecting on the original mapping's objectClass.

I tried running the existing development test suite before hand to verify my implementation wouldn't break any of them, but it had hundreds of failing tests right after cloning so I couldn't. It has been working on my own app, appreciate feedback of anything that this might unadvertly break.

[segiddins]

This will require test coverage to merge, thanks!

[valeriomazzeo]

@rafaelnobrepd would you be able to provide test coverage?

[rafaelnobrepd]

Hi, I actually took a quick look at this today, as it should be easy to add test coverage covering my own usage cases, but I realized it is breaking testInverseMappingWithNilDestinationKeyPathForAttributeMapping which was added when addressing #1116 . I would need some help understanding it to be able to fix it.