version $Id: _calendar.plugin.php 4159 2013-07-08 06:11:55Z yura $
and
@version $Id: _calendar.plugin.php 4555 2013-08-26 09:40:35Z yura $

1.Cellspacing not valid attribute
2.summary not valid attribute
3. 'attr'not valid attribute

Line 457 removed cellspacing="0" and replaced the word 'summary' with title
line 472 removed abbr="[abbr]"