Old docs should be placed in the new docs structure

[mvriel]

Google regularly points to the old documentation (manual.phpdoc.org); we should add rewrites that rewrites most pages to their new location (if available) and 302 the rest to the documentation landing page.

A new landing page should be introduced that will disambiguate between the v1 and v2 docs and the manual.phpdoc.org docs should be moved to the new url structure.

This issue was based on the feedback in http://www.reddit.com/r/PHP/comments/2aujmh/why_is_phpdocs_old_documentation_still_available/by