Changelog for s6.

In 2.5.0.0
----------

 - Added this NEWS file. :)
 - Major types overhaul to make them more POSIXly correct:
compatibility with skalibs-2.5.0.0.
 - Services can now report permanent failure by having a ./finish
script exit 125.
 - s6-svwait, s6-svlisten and s6-svlisten1 now exit the number of
services that reported permanent failure. They exit 99 on timeout.
 - When a service has a ./nosetsid file that contains "setpgrp", it
is run in a new process group, but not in a new session. If the
./nosetsid file contains anything else, the service is run in the
same session and process group as the supervisor, and if there is
no such file, it's run in a new session (same behaviour as before).
 - s6-log now writes a warning to stderr when it closes the stdout
stream.
 - s6-log's individual file size limit bumped to 256 MB.
 - Various bugfixes. (thanks jjk!)