Refactor list view to be closer as to how they're intended

... and use the classic ("deprecated") version, because that version
works better with icons to the left and right of list items etc.

Adds one "delete" icon per entry in the Magic Folder list view
as per #74.

Removes the static "might contain magic" text each entry in the
magic folder list view had. Closes #70.

Uses correct dividers. Closes #48.