UserStream: Add network monitoring
DefaultTimeline: Reset the timeline on network loss
UserStream: Add timeout back again

Additionally to the GNetworkMonitor, this should protect the stream in
the case that Twitter decides to kill the connection.
ITimeline: Also set max_id in load_newest
ITimeline: Care for max_id in load_newest again
Timelines: Add function property

So it can be automatically used. Should also replace the parameter for
all the load_ functions.
DefaultTimeline: add Connection loss handling

On connection loss, we do nothing, just nothing. Once we have a
connection again, we first check if there are any new tweets and if so,
we completely reset the timeline, remove all tweets and load the newest
again.
UserStream: Add a heartbeat timeout

...Which will keep track of the received heartbeats and restart the
stream if necessary.
UserStream: Don't remove the network timout in start()
UserStream: Add some debugging output
Merge branch 'continuous3'