Use upsert to simplify database updates

We very often insert an new value or update a value in a row. We can not simply override that column because we loose all other values in that row. So far we triy to insert and then to update if insert is not working. This creates much more code with branches which we have to maintain and to support. In the newest version of Sqlite there is support for upsert which only needs one command for it. We should not only use it but we should update in the long run the old code to it too. It is potentially faster too.