support Leybold turbo pump

This is the basics to starting to support Leybold turbo pumps, which have some peculiar quirks.

Also general improvements.

ebpfcat/ebpfcat.py

@@ -427,7 +427,8 @@ class FastSyncGroup(SyncGroupBase, XDP):
         await super().run()
 
     def update_devices(self, data):
-        self.current_data = data
+        if data[3] & 1:
+            self.current_data = data
         for dev in self.devices:
             dev.fast_update()
         return self.asm_packet