Fix the display of posts with HTML entities lacking a semicolon, and fix filtering posts by one user

ℵ Nonbreaking-space your posts with impunity!
ℵ Less scattered explanation for why you don't have PMs!
ℵ "Filter Posts by this User" goes beyond page one! (If this affected you, you'll need to log out and back in! Time to find that sticky note with your password!)