phpng, migration guide draft

hi, A page has been created today to document the migration to phpng (for those willing to do it before the rfc got accepted :): https://wiki.php.net/phpng-upgrading It would be nice to keep adding things not listed there as we found them. That will be amazingly helpful to port existing codes and write the final migration guide. Cheers, -- Pierre @pierrejoye | http://www.libgd.org