Add new profile features

[Didactylos]

Add new profile features:

• list of recent posts and threads this person created, on this and other projects.
• other features from social networking sites?
• Add ‘referral’ mechanism: new user creates account, enters email of ‘referrer’ (or goes to URL that has it embedded). Give referrer a fraction of credit (or a 1-time bonus). List referrals on user page (show only those still active). Add new referral table to DB.