New database system that uses PDO if present/Test script for doing database upgrades.

There is a new database class that uses PDO. With this it will be possible to support other systems than only MySQL. It uses DDDBL (http://www.dddbl.de/) as a database layer. In the future it will be able to use things like prepared statements.

Additionally there is a new script that will make database updates in the future. By now it only prints out what it would do, but it is doing nothing. This is done for safety reasons. I hope that some testers will tell, what the system would do. In the next step the script will be activated.