Added some events

Check it, yo:

	$('#someinput').mask("99/99/9999", {
		'onKeyPress': function(event) {
			// sum codes
		},
		'onKeyDown': function(event) {
			// sum codes
		},
		'onBlur': function(event) {
			// sum codes
		},
		'onFocus': function(event) {
			// sum codes
		},

		// Opposite of completed. Fires if valid input but not completed
		'incompleted': function() {
			// sum codes
		}
	});

The callback happens after the the end of the functions that alter the buffer and whatnot. Just look, you'll get it.