Add object.deepValuesOfType validator - fixes #51

[SamVerschueren]

Fixes #51.

Added the type definitions for is-plain-obj manually here. Will try to PR it to DefinitelyTyped when I find some time. Feel free to provide feedback in the meantime.

[kevva]

Did you discuss using the name deepValuesOfType? I get why valuesOfTypeDeep might be better, I usually put "modifiers" at the end too, but I think putting the deep in front in this case is clearer and sounds better and is also inline with equal/deepEqual.

[SamVerschueren]

Thanks for the feedback. We didn't discuss this. I'm fine with renaming it. I understand why the new name might be slightly better.

[sindresorhus]

Just use is.plainObject

[SamVerschueren]

How could I miss that :)!

[sindresorhus]

Let's go with deepValuesOfType.

[SamVerschueren]

Feedback processed.

[sindresorhus]

Perfect as always, Sammy :)

[SamVerschueren]

Haha, thanks 🍻