* Use binds rather than onFoo functions which aren't actually
   handler functions themselves but return them
 * Rename onKeyUp to moveSelectionDown etc,, reserving onKeyUp
   for "a key has been released" rather than, "the up arrow key
   has been pressed"

 * Pressing enter now always adds whatever was in the input box
   to the invite list, if it's a valid address (previously it
   added it to the list of it was a search result but submitted
   the form straight away if there were no results).
 * Remove isValidAddress as it was only used in the context of
   testing whether its return value was true or null (where null
   meant "unsure") so just use getAddressType instead.

…invitedialog

if input is empty

And fix typo where it was handled