Add timeout on close

Adds additional timeout wait on socket close in __exit__

Corrects for occasional duplicate ACK packet that caused a 0 len message to be read.

Author: AdamCummick

adafruit_wiznet5k/adafruit_wiznet5k_socket.py

@@ -118,6 +118,10 @@ def __exit__(self, exc_type, exc_val, exc_tb):
             if time.monotonic() - stamp > 1000:
                 raise RuntimeError("Failed to disconnect socket")
         self.close()
+        stamp = time.monotonic()
+        while self.status != adafruit_wiznet5k.SNSR_SOCK_CLOSED:
+            if time.monotonic() - stamp > 1000:
+                raise RuntimeError("Failed to close socket")
 
     @property
     def socknum(self):