v0.5.0 Autocomplete transformers

Custom transformers for autocomplete options! Now, you can specify a transformer function on an autocomplete option to transform the value before it is passed to the handler. (And the types will still be correct!) Have a custom autocomplete for dates? Now you can transform the string into a Date before it is passed to the handler. Use and autocomplete option that searches something from your database? Now you can get the database object passed right into the handler.