backward compatibility (this function was added in MySQL 4.1)
bug fixed: with chronology mode, PWG displays thumbnails on main page if
even if no category (which will soon be called "section") is set. This was
producing warnings on category.php from include/category_default.inc.php.
refactoring: on include/calendar_base.class.php and
include/functions_calendar.inc.php. Unix file format, coding guidelines,
etc. While trying to understand the code, I've made some presentation
modification to clarify variable names and so on.
git-svn-id: http://piwigo.org/svn/trunk@1053 68402e56-0260-453c-a942-63ccdbb3a9ee
