Feature request: A way to get an icon based on the lowercase-dashed-format

I am working on an application where we allow users to set an icon name. We'd refer them to https://feathericons.com/ and say we support any of those icon names. In this library, you get an element reference with PascalCase format, as is conventional for a React element. It'd be convenient to have a way to get a reference to a React element from a dashed-format name. Something like this:

```js
import * as Icon from 'react-feather';

...
const MyIcon = Icon.get('alert-circle');
// is now the same as
...
```