Only xmalloc if needed instead of doing worst case scenario.
Make it so on a call to start_msg_tree and it comes across a node
that is down we abandon the tree and send to each node serially.

Reference Bug 1216
Refactor of the forward_msg_t for more maintainable code.  No real code
change, just structure modification.
Make it so on a call to forward_msg and it comes across a node
that is down we abandon the tree and send to each node serially.

Reference Bug 1216
minor formatting fixes.