design related changes in R39

For Paid and Permanent users, ?style=mine is now available as a persistent preference with toggle on/off in the nav strip. More details in paidmembers here.
Graphic Previews (Snap) is now a viewer option rather than journal setting. More details in news here.
Changed "Change Journal Theme" to "Change Journal Style" and "Customize Journal Theme" to "Customize Journal Style" in the Journal menu on the main navigation.
HTML fix in Expressive and Mixit layouts (they were missing closing divs).
Fixed alignment in Writer's Block on the homepage.
Updates to Profile Beta.