RemoteShell now runs as a Python console if started as main script.

- Starts a framework and remote shell
- Runs a Python interactive console
- Waits for the console to return and cleans all up
MQTTClient: Explicitly stop the Paho loop when disconnecting

This ensures that the loop thread variable is internally set to None in
Paho, allowing loop_start() to start a new thread.

Also renamed start_time to start_timer and now using Paho methods to
convert result codes to strings.
RemoteShell client threads are now named according to client address