Move some user data into separate table(s)

The following discussion from !2623 (merged) should be addressed:

• @yorickpeterse commented on a discussion: (+3 comments)

  My main concern here is that our users table is already fairly wide. I'm wondering if it might not be a better idea to store these settings in some sort of user_settings and user_statistics (for the timestamps and such) tables. This would make updates on users more efficient, though it would also require more code. Perhaps it's best if we schedule that for 10.0 so we can also move over other columns?