Fixed a bug with SimpleRegionFile
- isClosed() = true did not guarantee that it was safe to open a new SimpleRegionFile with the same name
-- The map was updated after the update to the atomic variable checked by isClosed()
--- Added full syncing

- Removed closed AtomicBoolean, as it did nothing

- Fixes a bug with MappedRandomAccessFile
-- write pointer was not adjusted correctly after write
-- seek was always used before write anyway

- slight tweak to the block locks