Comment and/or doc changes. / Updating submodules. Pulls in: Comment and/or doc changes / (Shortened) Account for SHM-jemalloc session.lend/borrow_object() failing due to session-down.

Comment and/or doc changes. / Updating submodules. Pulls in: Comment and/or doc changes / (Shortened) Account for SHM-jemalloc session.lend/borrow_object() failing due to session-down. #844