New Global Constants
Changes to PHP Internals
Migrating from PHP 5.4.x to PHP 5.5.x
PHP Manual

## Changes to INI file handling

### Intl

The intl.use_exceptions configuration directive has been added, which controls the behaviour of intl when global errors occur in conjunction with the already extant intl.error_level configuration directive.

### MySQLnd

The mysqlnd.sha256_server_public_key configuration directive has been added to allow mysqli to use the new MySQL authentication protocol.