The group configuration parameter allow to share access to yggdrasil
control socket with the users in the system. In the version we propose,
it is null by default so that only root can access the control socket,
but let user create their own group if they need.
Remove User= durective in systemd unit. Should a user with the specified
name already exist in the system, it would be used silently instead of a
dynamic user which could be a security concern.
Since version 0.4 Yggdrasil works again using systemd's DynamicUser option.
This patch reenables it to improve security.
We tested this with both persistent and non-persistent keys. Everything
seems to work fine.
Favor the configuration in "configFile" over "config" to allow
"configFile" to override "config" without a system rebuild.
Add a "persistentKeys" option to generate keys and addresses that
persist across service restarts. This is useful for self-configuring
boot media.
