autocomplete() should trigger autocomplete event even when text already matches

Currently, [`autocomplete()`](https://github.com/corejavascript/typeahead.js/blob/78971040cc6c02f12100ed48b1d2f5719c04c5c6/src/typeahead/typeahead.js#L371) doesn't trigger the `autocomplete` event if the input text matches the given `$selectable`. Why should it, if autocompletion won't change the text?

Because there may be other data attached to the typeahead choice which is extracted by downstream logic listening for the event.

Instead of
```JavaScript
isValid = data && query !== data.val;
if (isValid && !this.eventBus.before('autocomplete', data.obj, data.dataset)) {
```
it should be just
```JavaScript
if (data && !this.eventBus.before('autocomplete', data.obj, data.dataset)) {
```