TSDocEmitter emits @defaultValue in a weird way

When parsing a comment like this: 

```
/** @defaultValue value */
``` 

and printing the parsed docComment using `TSDocEmitter` it will create this output:

```ts
/**
 * @defaultvalue
 *
 * value
 */
```

While this seems to be still working with IDEs it is quite ugly.

I think this can be fixed by using the same handling as with `@returns`. 