update TODO

TODO

@@ -3,12 +3,5 @@ Not necessarily ordered by priority:
 
 - IPv6 support.
 
-- Support relaying from external sources.
-
 - Support re-encoding of sources.
 
-- Better load balancing policies that take actual network usage into account,
-  which could be done using the reported icecast status information (this
-  is a bit problematic due to VBR streams and such), or by directly measuring
-  the system-level network throughput.
-