twistedActor 0.9.4

* Overhauled DeviceSet.replaceDev to make its behavior safer and more predictable:
    * Initialize the new device.
    * Disconnect the replaced device, instead of merely sending INIT.
    * Fixed a bug whereby DeviceSet would attempt to send a status command after disconnecting.
    * Replace the device even if connecting and initializing the new device fails.
* Fix a few minor documentation bugs and clarified one log message.