pgraph: Add fast pausing and exiting of graphs

This causes a graph to actually stop processing part way through, even
if there are poke's that want to continue on. This is so that the user
experience of pressing ^C actually causes a shutdown without finishing
the graph execution. It might be preferred to have this be a user
defined setting at some point in the future, such as if the user presses
^C twice. As well, we might want to implement an interrupt API so that
individual resource execution can be asked to bail out early if
requested. This could happen on a third ^C press.

lib/main.go

@@ -421,7 +421,7 @@ func (obj *Main) Run() error {
 			// run graph vertex LOCK...
 			if !first { // TODO: we can flatten this check out I think
 				converger.Pause() // FIXME: add sync wait?
-				G.Pause()         // sync
+				G.Pause(false)    // sync
 
 				//G.UnGroup() // FIXME: implement me if needed!
 			}