Implement ChanKeep joining functions

* Low-key channel joining with incrementally increasing delay
* Spin up needed instances to be able to cover a certain channel space
* Fix provisioning functions to prevent race conditions with lots of
relays being created at once
* Tweakable switchover from covering all channels to only covering
channels with more users than the mean of the cumulative user count

main.py

@@ -28,6 +28,7 @@ relayConnections = {}
 IRCPool = {}
 ReactorPool = {}
 FactoryPool = {}
+TempChan = {}
 
 MonitorPool = []