Add "autofillsinglematch" option to combobox:

if there is a single matching option, accept it even if user has not typed in the full text.
Usage: $("select").combobox({ autofillsinglematch:1 })
Example:  For the <select> element below, if the user types "bama", only "Alabama" will display in the autocomplete list.  If the user then presses the tab key or clicks elsewhere to lose focus, the autocomplete combobox will auto-fill with "Alabama".  This way, the user does not have to type in the entire matching text once there is only a single match.
```
<select id="state1">
	<option value=""></option>
	<option value="AL">Alabama</option>
	<option value="AK">Alaska</option>
	<option value="AZ">Arizona</option>
	<option value="AR">Arkansas</option>
</select>
```