[fixed] overzealous autocompletion

This PR changes the component so that it only autocompletes if the matched option starts-with (instead of contains) the user input.

If I start with an empty textbox and type "t", the component autocompletes to "Utah" (the "ah" being highlighted/selected).

This is bad because if the first key press were a typo, a user expects to hit backspace one time and end up with an empty textbox.  Instead, the textbox still contains "U".