Convert confirm dialogues to use the confirm renderer

There's about 40 instances of dialogues that hand-code the equivalent of the "confirm" renderer, i.e. producing a div#notice.generalbox.box with at least one button (often simply "continue").

Some of them vary the HTML slightly, which makes it hard to style them (e.g. putting the buttons outside of the div#notice , rather than inside it), and obviously any changes or improvments made to the renderer will not affect these bits of duplicated code.

You can find most of them with this command:

$ git grep -e box --and -e "'notice'"