dba and db extensions

Hi Markus, The main difference left between dba and db is that dba does not do any locking. We could easily add this by copying the necessary parts from the db extension. However we would need to change the resource type to also keep the lock information. Otherwise a crashed php or one that does not store the dba_open result would leave the lockfile locked. However i tested this with the flatfile support and it did not work this way. I had to keep the lock file open until the dba_close() call. But when keeping the file open it worked as expected and even multiple reades, read during write and killing of the writer process worked as expected. marcus