…er as third arg

It makes no sense for the singular translate method to allow both at the
same time. It causes developers to add a `undefined` just to be able to
pass option. So allow one of both as the third parameter and deprecate
the 5-parameters overload so we can remove it in v4.

Before:
```js
translate('app', 'Number: %n', undefined, 4)
translate('app', 'Hello {name}', { name: 'John' })
translate('app', 'See our {linkStart}documentation{linkEnd}.', { ... }, undefined, { escape: false })
```

After:
```js
translate('app', 'Number: %n', 4)
translate('app', 'Hello {name}', { name: 'John' })
translate('app', 'See our {linkStart}documentation{linkEnd}.', { ... }, { escape: false })
```

Signed-off-by: Ferdinand Thiessen <[email protected]>