No sidebars

How about this?

Sorry to keep replying to my own post, but now that I have some more time, I thought I'd add some explanation. I think the current dev release would work fine for an initial install. But coming from a 5.x install, my blocks are defined as appearing in $sidebar_left and $sidebar_right, not $left and $right. So they don't show up. Upgrading users could go to Administer>Site Building>Blocks, and fix this, but for more complicated sites, that could involve a lot of re-configuration.

Keeping the sidebars as $sidebar_left and $sidebar_right makes for a simpler upgrade path.

I looked for other instances of $left and $right, in other files, but didn't find any. I did find some #sidebar_left and #sidebar_right selectors still in the print_css and style_css.