db_maintenance 6.x-2.0-beta1

New features from the 5.2 branch merged across;

• detect failure of optimize and optionally execute a repair table
• allowed option to not optimize tables by setting frequency to "never"
• added option to backup database, requires access to exec() some ISP's block this, and proper path to mysqldump
• added option to backup files directory, requires access to to exec(), and proper path to tar
• added option to email user(s) when database and files are backed up