support for multiple confirmations

Suppose the channel is in confirm multiple mode, and acks for the
following messages are outstanding:

>  3 4 5 7 10 13

The server sends one confirm-up-to 5 ack and three more acks for 7, 10
and 13.

If the client receives a basic.ack, it should interpret it like this:

  basic.ack{delivery-tag=N, multiple=false} => the published message
    with sequence number N has been handled

  basic.ack{delivery-tag=N, multiple=true} => all the published
    messages with sequence numbers up to and including N have been
    handled

0 files changed, 0 insertions, 0 deletions