New "INSERT only" backend for CMS

I've updated the storage engine of my cms to only make INSERTs and no UPDATEs on database level. Current objects are always retrieved by intelligent SELECTs. This has a number of convenient consequences, especially considering version tracking and history. Having lots of updates of course will bloat the database size. I'll have to find a solution for that. Also there will be problems with enabling/disabling stories and finding the correct version to display.