some rework
QFix ChannelsStore.publish
qfix optimize imports
Fix ChannelsStore.publish call args
QFix ChannelsStore.publish event msg
add TODO "add methods create_chatroom/remove_chatroom/etc"
Fix ChannelsStore.publish "RuntimeError: set changed during iteration"
change wamp_example. add channel 'chat:room'
Merge branch 'wamp2' into rework-broker
FIX tests
refactor ChannelsStore. move actions to broker
new class Bidict
store subscription_id for subscribe
move ChannelsStore actions to Broker
refactor Bidict rename keys->by_key, values->by_value
new Bidict.pop like a dict.pop
Broker.unsubscribe
Broker with publication|id
add TODO remove transport from _transports_by_topic -> Broker.process_unsubscribe
FIX Broker.process_unsubscribe removing transport