tree-wide: remove Emacs lines from all files This should be handled fine now by .dir-locals.el, so need to carry that stuff in every file.

util-lib: move string table stuff into its own string-table.[ch]

core: extend KillUnit() to return error when no unit was killed

util: split out signal-util.[ch] from util.[ch] No functional changes.

remove unused includes This patch removes includes that are not used. The removals were found with include-what-you-use which checks if any of the symbols from a header is in use.

core: introduce new KillMode=mixed which sends SIGTERM only to the main process, but SIGKILL to all daemon processes This should fix some race with terminating systemd --user, where the system systemd instance might race against the user systemd instance when sending SIGTERM.

core: optionally send SIGHUP in addition to the configured kill signal This is useful to fake session ends for processes like shells.

unit: split off KillContext from ExecContext containing only kill definitions