executable in python3

dirty modification to allow execution in python3 as well.

examples/echoapp_client.py

@@ -1,5 +1,8 @@
 import websocket
+try:
     import thread
+except ImportError:  #TODO use Threading instead of _thread in python3
+    import _thread
 import time
 import sys
 
@@ -29,7 +32,11 @@ def on_open(ws):
         ws.close()
         print("Thread terminating...")
 
+    try:
         thread.start_new_thread(run, ())
+    except:
+        _thread.start_new_thread(run, ())
+
 
 if __name__ == "__main__":
     websocket.enableTrace(True)