Copyright (c) 2009 Sergiy Kovalchuk (serg472@gmail.com)
Copyright (c) 2015 Rob Calcroft - For jquery-loadmask-plus
Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php) and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
Following code is based on Element.mask() implementation from ExtJS framework (http://extjs.com/)