How to set `undefined` by `dot.set`

[winjeysong]

Thanks for your big work on maintaining this library. It helps me a log!

But now, I faced a problem.

dot-object/src/dot-object.js

Lines 425 to 428 in a95a7fc

	// Do not operate if the value is undefined.
	if (typeof val === 'undefined') {
	return obj
	}

Due to the code above, I can't set undefined like that:

const o = { foo: { bar: 'baz' } };
dot.set('foo.bar', undefined, o); // not work

So is there a way to set undefined by dot.set ? Or just remove the code I mentioned above, and library users can do what they want.