Fix disappearing top cell separator in basement.

Things that didn't work:

* Setting the table view's separatorStyle to None and back in
  -tableView:didSelectRowAtIndexPath:.
* Ditto in -tableView:didHighlightRowAtIndexPath: or ...Unhighlight....
* Selecting then deselecting a cell after loading.
* Messing with cells' separatorInset.

Thing that worked but was untenable:

* Setting the table view's allowsSelection to NO. Now the basement is useless.
Formatting.
Formatting and improved Themes.plist usage.