A lot of improvements, fixes and polishing

README.md

@@ -1,6 +1,9 @@
 # mp3printer
 a mp3 printer, written in python and jquery with websockets
 
-You need python3, vlc, vlc bindings for python, youtube-dl and tornado. Start by running ```sudo sh startup.sh``` and the mp3 printer will listen for http requests at port 80.
+You need python3, vlc, vlc bindings for python, yt-dlp and tornado, optionally pychromecast for casting support. Start by running `sudo ./startup.sh` and the mp3 printer will listen for http requests at port 80.
+Running `./startup.sh --help` will show a list of possible options.
 
 Record scratch sound is by "Raccoonanimator" and can be found here: https://freesound.org/people/Raccoonanimator/sounds/160907/
+
+Icon is a combination of two icons from the [Tango Desktop Project](http://tango.freedesktop.org/).

connections.py

@@ -2,11 +2,12 @@
 import json
 
 class Connections:
-    def __init__(self):
+    def __init__(self, ioloop):
         self.lock = Lock()
+        self._ioloop = ioloop
         self._clients = []
 
-    def add_conneciton(self, handler):
+    def add_connection(self, handler):
         self.lock.acquire()
         try:
             self._clients.append(handler)
@@ -20,11 +21,10 @@ def close_connection(self, handler):
         finally:
             self.lock.release()
 
-
     def message_clients(self, message):
         self.lock.acquire()
         try:
             for client in self._clients:
-      		        client.write_message(json.dumps(message))
+                self._ioloop.add_callback(client.write_message, json.dumps(message))
         finally:
             self.lock.release()