Add DIR to Forefront Antispam Report header

[sevmonster]

Does not appear to be documented, but I am seeing it on emails. DIR seems to be set to either INB for inbound and OUT for outbound. Right now it shows up under Unknown fields.

[stephenegriffin]

Until we have some sort of documentation for it I'd only be guessing. I did work to make sure that unknown fields like that get rendered somewhere so analysts still have access to them

[stephenegriffin]

Closing old bugs