Fixes and changes for Seditio version 125

- Enhanced parser, now you can add your own BBcodes.
- Full compatibility for UTF-8 encoding.
- New installations are UTF-8, for existing sites the user can decide to upgrade or not.
- One less file include resulting in a speed gain between 5% and 10%, depending of the platform.
- Many enhancements to the administration panels.
- Performance tweaks in the core files and in some plugins.
- Various tweaks an enhancement to the pagination system.
- Enhanced default skin (now named 'cadmium').
- Built-in XML Atom syndication.
- Added support for extra PHP files when installing/un-installing plugins.
- PHP 5.3 compatible (so should be PHP 6.0 compatible).
- The bug fixes and enhancements are detailled in the Project tracker.