Refactored packets

this patch removes the need for dacite2 package for creating
packet objects from the aprslib decoded packet dictionary.

moved the factory method from the base Packet object
to the core module.

tests/test_plugin.py

@@ -45,7 +45,6 @@ class TestPluginManager(unittest.TestCase):
         self.assertEqual([], plugin_list)
         pm.setup_plugins()
         plugin_list = pm.get_plugins()
-        print(plugin_list)
         self.assertIsInstance(plugin_list, list)
         self.assertIsInstance(
             plugin_list[0],
@@ -163,9 +162,7 @@ class TestPluginBase(TestPlugin):
         self.assertEqual(expected, actual)
         mock_process.assert_not_called()
 
-        packet = fake.fake_packet(
-            message_format=core.PACKET_TYPE_ACK,
-        )
+        packet = fake.fake_ack_packet()
         expected = packets.NULL_MESSAGE
         actual = p.filter(packet)
         self.assertEqual(expected, actual)