Major Description
Currently our javadocs point to using SimpleFSDirectory "to avoid ClosedByInterruptException".
But this is really bogus. If you interrupt() a thread doing i/o, then you need to be prepared for the consequences. Its just that RAF is broken and not interruptible at all, but that shouldnt justify us continuing to use it.
SimpleFSDirectory should be "the most portable", so it should use Files.newByteChannel. And we should remove the javadocs/warnings about ClosedByInterrupt