Remove pointless methods and usage

[lukemorton]

The following methods should be removed:

// Move to position just before word
$('input').caret('hello');

// Move to position just after word
$('input').caret('hello', true);

// Move to offset from word's beginning
$('input').caret('hello', 6);

And so should $.fn.caretToStart which is longer than just using $.fn.caret(0).