Add OCConnectionChannel class
Add OCHeartbeatChannel class
Add OCReceiverControlChannel class
Make the constants constant
Add missing namespaces
Add comment about subclasses implementing did{Connect,Disconnect}
Add headers to OpenCast.h
Add -[OCDeviceManager prepareBaseChannels] method
Send -didConnect and -didDisconnect messages to channels as appropriate
Disconnect channels from the OCDeviceManager when they're removed
fixup after prepareBaseChannels
Prepare connection and heartbeat channels after connecting