Add option for not selecting first list item by default, unselect with arrow keys

[pjsier]

• Adds selectByDefault option that defaults to true, but if set to false it won't select the first item in a result list automatically.
• Allows users to submit input with the enter key that is not a list item even if results are displayed.
• Setting it to false also allows users to unselect items in a list by moving outside the bounds of a result list with the arrow keys.

The use case for this came from having Horsey in a search field where I wanted people to be able to have autocomplete as a shortcut, but also be able to submit more general queries and get redirected to a page with results. For the example this would be just pressing enter to search for all results containing "apple" rather than having to pick one of the displayed options with "apple" in it.