Features:
+* resolved:
+ - IDN (?)
+ - DNSSEC
+ - LLMNR
+ - mDNS/DNS-SD
+ - DNS-SD service registration from socket units
+ - port sd-resolve to direct bus calls
+ - nss module: fallback to glibc dns modules if resolved cannot be contacted
+ - edns0 + dname
+ - cname on PTR (?)
+ - negative caching
+
* Allow multiple ExecStart= for all Type= settings, so that we can cover rescue.service nicely
* the resolv.conf tmpfiles line should be covered by ENABLE_NETWORKD...