MSRE - Make sure 'default' rule is the last

Moved isset($_POST[$target]) test up to ensure default rule is recognised as such
MSRE - Fix 'default' direction handling
MSRE: Really fix default direction

"default" direction can only be "FromOrTo:" or "Virus:"
Merge pull request #59 from philrandal/master

MSRE: Make sure 'default' rule is the last