Requirements on server side

Since a simple log file is very unhandy to investigate, the error data should be logged into the database. Sorting and filtering is much easier then.
This implies a DOS protection since endless loops in the front-end would knock the server out.
→ This protection should be implemented in front-end too!
It should be possible to clean the DB in a simple, periodically way (like a cronjob or something).

In addition we should add a php shutdown function to get fatal errors in the normal php logging to (see satnam shop)