fixup! core/network.py: Implement a class that runs Man-in-the-middle attacks
ui/mainwindow.py: Rename "Pause" option to "Stop"

First of all, because "pause_control()" isn't yet implemented. Also,
because "restart control" is in the roadmap but it's not going to be
addressed in this development iteration.

In the renaming process, I've found a problem in
`MainWindow.stop_control()`. It was treating the whole string of the
selected option as if it had the IP address separated from the status by a
space. Because it's being displayed as "<ip_address>:<status>", the string
needs to be split using the colon.
api.stop_control: Stops and removes the control

The use case of "stop control" is to completely stop it, tear down anything
related to it that is not going to be useful anymore, and remove it from
the system.

What this function was doing before is something similar to what "pause
control" is going to do.