A......... [ZBX-8493] Fix usergroup.massadd API call to not create duplicate entries in "rights" table.

git-svn-id: svn://svn.zabbix.com/trunk@47548 f4e7fd02-d210-4e34-a1e0-d4093fb66cc2
..F....... [ZBX-8478] Fix slideshow handling in monitoring for slideshows without slides.

git-svn-id: svn://svn.zabbix.com/trunk@47551 f4e7fd02-d210-4e34-a1e0-d4093fb66cc2
.......... [ZBX-954] unify spelling of 'non-zero'; thanks to volter for spotting

git-svn-id: svn://svn.zabbix.com/trunk@47564 f4e7fd02-d210-4e34-a1e0-d4093fb66cc2
.......... [ZBX-954] frondend -> frontend

git-svn-id: svn://svn.zabbix.com/trunk@47565 f4e7fd02-d210-4e34-a1e0-d4093fb66cc2