Add reporter hook.

The hook being added is:

bool HookReporter(const std::string& prefix, const EventHandlerPtr event,
                  const Connection* conn, const val_list* addl, bool location,
                  const Location* location1, const Location* location2,
                  bool time, const std::string& buffer) override;

This hook gives access to basically all information that is available in
the function in Reporter.cc that performs the logging. The hook is
called each time when anything passes through the reporter in the cases
in which an event usually would be called. This includes weirds. The
hook can return false to prevent the normal reporter events from being
raised.

src/plugin/Plugin.cc

@@ -208,6 +208,16 @@ void HookArgument::Describe(ODesc* d) const
 		d->Add("}");
 		}
 		break;
+
+	case LOCATION:
+		if ( arg.loc )
+			{
+			arg.loc->Describe(d);
+			}
+		else
+		 {
+			d->Add("<no location>");
+		 }
 	}
 	}
 
@@ -393,6 +403,14 @@ bool Plugin::HookLogWrite(const std::string& writer, const std::string& filter,
 	return true;
 	}
 
+bool Plugin::HookReporter(const std::string& prefix, const EventHandlerPtr event,
+			  const Connection* conn, const val_list* addl, bool location,
+			  const Location* location1, const Location* location2,
+			  bool time, const std::string& message)
+	{
+	return true;
+	}
+
 void Plugin::MetaHookPre(HookType hook, const HookArgumentList& args)
 	{
 	}