camel_service_get_settings() is now camel_service_ref_settings()
and it returns a new CamelSettings reference which the caller must
release with g_object_unref().
These libraries are bound for E-D-S so they live at the lowest layer of
Evolution for now -- even libeutil can link to them (but please don't).
This is the first step toward moving mail handing to a D-Bus service.
