taggart

Also, the default compiler section could use an $EXTRAOPTIONS in the final linking line so that it's possible to just set `EXTRAOPTIONS="-lstdc++fs"` at the top when using older g++

Thinking about this more... Does sympa have any policy about scenari changes? Looking at the [default scenari](https://github.com/sympa-community/sympa/tree/main/default/scenari) it seems they don't change very often, so maybe it has not come...

Oh and with a introduction explaining things and common variables, etc

Also why you'd want it in general. Does it help you pass restrictive firewalls? Are there latency advantages? it is more resilient in the face of low bandwidth or packet...

This would still be nice to have! For other people running into this, the solution for now is to specify all of them. So run `gnt-cluster info` and record what...