Currently migrating to .NET-Core 3.1 .NET 5.0

See #302

netcore

• Crash when open link (documentation, update, etc.)
• Fix update check (assembly version not working?)
• Restart as admin does not work
• Fix open network connections
• Fix Clear dns cache
• Fix Release & Renew
• Fix apply network config
• Fix Embedded PowerShell
• Fix Embedded PuTTY
• Fix Embedded TigerVNC

MahApps

• Update all necessary resource keys so that the application no longer crashes
• Fix ContextMenu style
• Fix Expander style for profiles (design, icon size/position)
• Fix Dragablz tab content (not transparent?)
• Fix ToolTip style
• Fix theme manager
  • Display BaseColorScheme in settings
  • Display Theme/Color in Settings
  • Fix Theme/Color translation
  • Fix ComboBox/ToolTip translation
  • Fix Settings
  • Fix AppearanceManager
• Icon color fixed
• Remove deprecated code / styles

list is not complete 😢 ...