New MailScanner Installer (msinstall) v5.00

Changes:

• Added BETA support for DirectAdmin on RHEL/CentOS/CL v7 and v8. This application will NOT function on DirectAdmin servers without our MailScanner Front-End product
• Update MailScanner code from v5.3.3 source and apply WTTW fixups
• Added support for new Exim named queues method for MailScanner when using MSFE – requires Exim v4.93+
• RHEL/CentOS/CL v8.1 OS support
• Moved /usr/mscpanel to /usr/msfe (symlink added for backwards compatibility)
• Renamed /usr/msfe/mscpanel.pl to /usr/msfe/msrules.pl (symlink added for backwards compatibility)
• Added run of msrules.pl and sa-update to mailscanner_daily.cron