The EModule, EExtensible and EExtension classes as well as the
e_type_traverse() function have been moved to Evolution-Data-Server's
libebackend library to replace e-data-server-module.c.
Now Evolution-Data-Server modules use the same framework as Evolution.
We track Evolution's online state separately from network availability
these days. I think there was still logic here from when we set online
state directly. Don't lie about network availability.
This demonstrates how to extend EShell without having to modify and
recompile e-shell.c. If NetworkManager integration is enabled, the
extension is loaded automatically when the EShell is created.
The same pattern can be applied to integrate other network monitoring
software like ConnMan or Microsoft's Wireless Zero Configuration.
