Mystify Soccer - Mail clearance

Mail clearance

Due to the amount of mail in mailboxes that is not being deleted by managers I have written some code to start clearing these redundant messages out.

This won't affect anything important but will include all read messages that are over 4 weeks old and have not been sent by a current manager. This includes mail from the game engine and managers that have left the game.

This change will assist me in keeping the database to a reasonable size.

One of my future tasks is to add a 'select all' button to the list of mail in a mailbox so it can be deleted quicker by the managers themselves.