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.

resolved: teach resolved the difference between "routing" and "search" domains Following the changes to expose the "routing" and "search" domain concepts in networkd, actually make resolved use them. It will now use routing domains exclusively for making DNS routing decisions, and use search domains additionally for extending single-label names.

resolved: fully support DNS search domains This adds support for searching single-label hostnames in a set of configured search domains. A new object DnsQueryCandidate is added that links queries to scopes. It keeps track of the search domain last used for a query on a specific link. Whenever a host name was unsuccessfuly resolved on a scope all its transactions are flushed out and replaced by a new set, with the next search domain appended. This also adds a new flag SD_RESOLVED_NO_SEARCH to disable search domain behaviour. The "systemd-resolve-host" tool is updated to make this configurable via --search=. Fixes #1697

resolved: add a generic DnsSearchDomain concept With this change, we add a new object to resolved, "DnsSearchDomain=" which wraps a search domain. This is then used to introduce a global search domain list, in addition to the existing per-link search domain list which is reword to make use of this new object too. This is preparation for implement proper unicast DNS search domain support.