Export more than one page #412

Export more than one page. A business site needs Home, About, Services and Contact, and right now the ZIP is a single index.html.

Shared nav and footer across pages, relative links that work from a file:// folder and from a host, and the frames folder shared rather than copied per page.

Done when: a site with four pages exports, every internal link resolves in the extracted folder, and the ZIP does not grow by a frame set per page.