First working draft
Added PHP extensions Xdebug and Zend OPcache for most PHP instances
Restructuring, fixes and updates

- Moved build/target config into seperate Makefile
- PKG: Updated PHP-5.4 version
- PKG: Use SCM master branch for PHP extension Xdebug and build for all
  PHP instances
- PKG: Build Zend Optimizer+ only for PHP <= 5.5
- PKG: Use updated PHP pkgbox file with Zend OPcache enabled by default
- Place demo index.php in default V-Host with call to phpinfo()
Some more target variables

- WWW_SERVER_NAME
- WWW_SERVER_ADMIN
- HTTP_PORT
- HTTPS_PORT
- FCGID_DEFAULT_PHP_WRAPPER
Changed rule for PHP extensions from multi-target into pattern rule
Created macro for loading a PHP Zend extension
Use fixed pkgbox version
Changed check for unset/empty PKGBOX_BUILD in rule clean
Added target variable WWW_ROOTPATH
Added README stub
Added demo self-signed SSL certificate
Fix for WWW_ROOTPATH replacement