Posposal: a new version of the specification #60

Hi there,
I'm the developer of gear lever, application to manage appinages.

The last couple of years I received multiple feature requests for my app, things that I've learnt about the user experience that I want to propose here, as a new or updated version of the spec.

1. All Appimages must be able to return their metadata without being fully exacted, which a command like option that must be built in
2. The current update system is ok but is limied, I would propose embed a static INI file inside the appimage package, that can be retrieved with a terminal command
3. Appimages should be able to list their features with a terminal command, for example: updates, desktop-integration etc .., Right now, there is no way to know if an app supports the --appimage-extract or not.
4. Should not rely on fuse2 anymore, some developers already found a way to do this

Let me know what you think