Add "classify" keyvalue to override monster classification.

src/dlls/turret.cpp

@@ -992,7 +992,15 @@ int CMBaseTurret::MoveTurret(void)
 int	CMBaseTurret::Classify ( void )
 {
 	if (m_iOn || m_iAutoStart)
-		return	CLASS_MACHINE;
+	{
+		if ( m_iClassifyOverride == -1 ) // helper
+			return CLASS_NONE;
+		else if ( m_iClassifyOverride > 0 )
+			return m_iClassifyOverride; // override
+		
+		return CLASS_MACHINE;
+	}
+	
 	return CLASS_NONE;
 }