Allow users to attach one public and one private comment to each submission

[erdman]

At the time of botcode submit, I suggest two text boxes to accompany the new version of botcode. "Public comment" would be viewable by all competitors on the Recent (submissions) History portion of the user's profile page, and would be attached to that submission version. Some might decline to use it, but others (like me) might like to be able to sort of announce what's new/improved, like "Improved mining", "Better combat", "Parameter tuning", "Fixed timeouts", etc. "Private comment" would be viewable only by the submitter, as a more detailed reminder of the specific features/improvements introduced in that version of botcode.