Add-ons for Veyon 4.4.1

[tobydox]

The add-ons package for Veyon 4.4.1 contain several improvements in the NetworkDiscovery add-on:

• NetworkDiscovery: implement session scanning for all hosts instead of localhost only
• NetworkDiscovery: display purchase info only when actually in use
• NetworkDiscovery: always show "Scanning" label until any host found

The installers are available for download at https://github.com/veyon/addons/releases/tag/v4.4.1