Changes to INI file handling

PHP 5.3.0 has significantly improved performance and parsing of INI files, and adds several new syntax features.

The standard php.ini files have been re-organized and renamed. php.ini-development contains settings recommded for use in development environments. php.ini-production contains settings recommended for use in production environments.
There is now support for two special sections: [PATH=/opt/httpd/www.example.com/] and [HOST=www.example.com]. Directives set in these sections cannot be overridden by user-defined INI files or at runtime. More information about these sections can be found here.
zend_extension_debug and zend_extension_ts have been removed. Use the zend_extension directive to load all Zend Extensions.
zend.ze1_compatibility_mode has been removed. If this INI directive is set to On, an E_ERROR error is emitted at startup.
It is now possible to use the full path to load modules using the "extension" directive.
"ini-variables" can now be used almost anywhere in a php.ini file.
Runtime tightening of open_basedir restrictions is now possible.
It is now possible to use alphanumeric or variable indices in INI option arrays.
get_cfg_var() is now able to return "array" INI options.
A new directive, mail.add_x_header, has been added.
user_ini.filename is new
user_ini.cache_ttl is also new
exit_on_timeout is new too
open_basedir is now PHP_INI_ALL

The following new ini directives have been added:

user_ini.filename and user_ini.cache_ttl for the new .htaccess-style user INI file mechanism.
Added mbstring.http_output_conv_mimetype. This directive specifies the regex pattern of content types for which mb_output_handler() is activated.
Added request_order. Allows controlling which external variables will be available in $_REQUEST.

The following ini directives have new default values: