* added more control over log file synchronization behavior (async, fsync,...

* added more control over log file synchronization behavior (async, fsync, fdatasync, O_SYNC, O_DSYNC)
* added optional pseudo-synchonous mode (similar to PostgreSQL write ahaed log), requests are immediateley acknowledged and written out to the disk log in batches every X ms.

git-svn-id: https://babudb.googlecode.com/svn/trunk@38 d4c7dd96-b7b2-11dd-893d-d98698f66bbf