Make PKC compatible with Python 3.6 again

resources/lib/plexbmchelper/listener.py

@@ -5,7 +5,8 @@ Plex Companion listener
 """
 from logging import getLogger
 from re import sub
-from http.server import ThreadingHTTPServer, BaseHTTPRequestHandler
+from socketserver import ThreadingMixIn
+from http.server import HTTPServer, BaseHTTPRequestHandler
 
 from .. import utils, companion, json_rpc as js, clientinfo, variables as v
 from .. import app
@@ -225,7 +226,14 @@ class MyHandler(BaseHTTPRequestHandler):
             self.response(v.COMPANION_OK_MESSAGE, headers)
 
 
-class PKCHTTPServer(ThreadingHTTPServer):
+class ThreadedHTTPServer(ThreadingMixIn, HTTPServer):
+    """
+    Using ThreadingMixIn Thread magic
+    """
+    daemon_threads = True
+
+
+class PKCHTTPServer(ThreadedHTTPServer):
     def __init__(self, client, subscription_manager, *args, **kwargs):
         """
         client: Class handle to plexgdm.plexgdm. We can thus ask for an up-to-