Use proj4.defs through the function, not the object

```js
proj4.defs('name');
```
instead of
```js
proj4.defs['name'];
```
and
```js
proj4.defs('alias', proj4.defs('name'));
```
instead of
```js
proj4.defs['alias'] = proj4.defs['name'];
```
I think internally it makes sense to use the object, which should be slightly more efficient. But I'm happy to change if you insist :smile:.