Getting ready for 4.1 Beta 2

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
More import/export support info on ReleaseNotes

Signed-off-by: Miika Turkia <miika.turkia@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
ReleaseNotes.txt: mention that unused cylinders are no longer shown

See #504

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>