jquery.byteLimit fixes:

jquery.byteLimit fixes:
* 'this' in a fn/prototype context already points to the jQuery object. Calling $(this) is redundant and goes through $.fn.init again untill it reaches the last else case (luckily $.fn.init() has a failsafe case for that, but also makes it harder to spot)
* Adding support for using the current attribute value (to avoid having to duplicate the values between PHP and JavaScript). Fully backwards compatible, I think it's a very handy feature to be able to pass a custom length, but using the maxLength attribute as a default makes sense.