! We don't use this setting any more, so let's stop offering it. But we need to retain it for the time being because actually fixing it is a major headache for this round of changes.

Signed-off-by: Peter Spicer <sleeping@myperch.org>
! attachmentEncryptFilenames isn't used any more, so clean it up. Fixes #594

Signed-off-by: Peter Spicer <sleeping@myperch.org>