Feature request: ability to escape dot in the key string

```js
const obj = {
"a.b": {
"c": 1
}
}
```

There are cases when object keys already have a dot in the name.
It would be nice to be able to escape the dot so that the split will pass through.

So
```js
dlv(obj, 'a\.b.c') === 1 // true
```