irkerd.xml: Cleanup syslog docs and shift 'os' import

This fixes some issues with 672240a (Use syslog facility when irkerd
is backgtrounded and no -l was given, 2014-05-31):

* Shift the 'os' import to keep the stdlib imports alphabetized.
* Move the syslog docs from a stand-alone paragraph into the
  -d/--log-level section.
* Add some text to the -d/--log-level docs explaining the distinction
  between the -l/--log-file traffic logs and the -d/--log-level
  program-tracing logs.
* StreamHandler logs to standard error (not standard output) by
  default [1].  Change "stndard output" to "standard error".
* Add articles to background and foreground ("the background").
* Fix a "packground" -> "background" typo.
* Explain our background-detection logic, and point out some of the
  assumptions made by the current implementation.  I still think that
  it's better to have an explicit --syslog setting, and to leave it to
  packagers/users to descide explicitly if they prefer logging to
  syslog or stderr.  But whatever the syslog-switching logic is, it
  should be clearly documented so folks don't have to read the source
  to understand it.

[1]: https://docs.python.org/3/library/logging.handlers.html#logging.StreamHandler

Signed-off-by: Eric S. Raymond <esr@thyrsus.com>
Better behavior in case stdout was closed when irkerd was backgrounded.
Remove an obsolete assumption and fix some markup.
Add support for using CertFP to auth to the IRC server, and document it.

Signed-off-by: Eric S. Raymond <esr@thyrsus.com>
Add a missing import.
Host option, as contributed by wking.
News update.
Clean up after recent pylint changes.
Version bump for release.