Features:
+* busctl: add a pcap writer, using LINKTYPE_DBUS/231
+
* man: maybe use the word "inspect" rather than "introspect"?
* introduce machines.target to order after all nspawn instances
* sd-event
- allow multiple signal handlers per signal?
+ - document chaining of signal handler for SIGCHLD and child handlers
* in the final killing spree, detect processes from the root directory, and
complain loudly if they have argv[0][0] == '@' set.