Packaging

• Adds a new cargo feature flag no-self-update. When used, Ajour won't check for
  newer updates.
• Adds 2 new release assets, one for Windows and Macos, both with this feature
  activated. These can be picked up by Chocolatey & Homebrew respectively.

Added

• Addons can now be exported to a .yml file and reimported to Ajour. When
  importing, any addons that don't currently exist on the system will be installed.
  Export and Import buttons have been added to the Addons section of Settings.

Fixed

• Fixed bug where alt+tab would change tabs in Ajour.