Ability to do 'accent insensitive' searches

Hey Andreas,

Great job with the instaFilta plugin! One requirement I had in a project I'm currently working on was to be able to do 'accent insensitive' searches (e.g. the search term 'jose' will match both 'jose' and 'josé'). Since the project was already using your plugin (and it works great!), I decided to fork the repo and extend it so it can also support this functionality. I made my best to respect the coding practices / style I have observed in this codebase. Do you think this feature will also be useful to other users? Maybe we can expand the `accentsToFind` and `replaceWith` options default values so they will also work nice for other languages? The default values I put are perfect for Portuguese and probably good for a couple other languages too.

Greetings from Brazil,

Alex.