interop & InOrder

[Doug Davis <dug@us.ibm.com>]

In the past when we did RM interops
we only tested InOrder DA - right now the interop doc is silent on this.
 I've been assuming we'd be doing InOrder again this time but I wanted
to know what other people's assumptions were.  If people agree we
should add that to the doc - and if we do then we can change the <LastMessage>
element to be a simple boolean-type of flag (e.g.  <LastMessage/>)
instead of including the last msg # in it.   

thanks,
-Doug