The message block "in transit" is buffered until acknowledged by the
receiving node.
In case the receiving node crashed, the buffer is sent again when
the connection is re-established.
In case the subscriber reconnected to another node, the resent messages
are forwarded to that new node.

Messages from the queue that are published to the subscriber were saved
in a backup queue and released (=deleted from persistent storage) before
they were delivered/acknowledged by the client.
Now the messages are only released when the acknowledge is received.

Remove excess blank lines

Co-authored-by: Dairon Medina Caro <dairon.medina@gmail.com>

This avoids high cpu due to needless looping.