Checkpointing the dynamic plugin code.

This is essentially the code from the dynamic-plugin branch except for
some pieces that I have split out into separate, earlier commits.

I'm going to updatre things in this branch going forward.

src/Event.cc

@@ -6,6 +6,7 @@
 #include "Func.h"
 #include "NetVar.h"
 #include "Trigger.h"
+#include "plugin/Manager.h"
 
 EventMgr mgr;
 
@@ -77,6 +78,9 @@ EventMgr::~EventMgr()
 
 void EventMgr::QueueEvent(Event* event)
 	{
+	if ( plugin_mgr->QueueEvent(event) )
+    	return;
+
 	if ( ! head )
 		head = tail = event;
 	else
@@ -115,6 +119,8 @@ void EventMgr::Drain()
 
 	SegmentProfiler(segment_logger, "draining-events");
 
+	plugin_mgr->DrainEvents();
+
 	draining = true;
 	while ( head )
 		Dispatch();