Improvements and fixes

A network scan at a plant now shows devices while it is still running.

• On a large plant, the device list fills batch by batch during a scan instead of only when the scan finishes.
• A device that answers only sometimes now turns up in a scan, which probes each address twice and more gently.
• When two-factor sign-in is set up, the authenticator app now saves the entry under "Mirox".