file_handler:
  Allow derived classes to add directory-listing behavior.
  unquote pathnames from the url.

FileLogger: new class.
StderrLogger: use FileLogger.
redirect_stderr: overwrite the copies in coro._coro as well.
  (otherwise a latency warning will cause the daemon to exit).

Removed non-existent dependency.

This way log processors don't have to duplicate it.

Adding E501 is working around a pep8 tool regression and should
be reverted when a fix is available.

Binary logging

Fix some readline issues with backdoor client

Facility: prepend each line with a facility id.
NoFacility: for one-module scripts.
StderrRedirector: capture stderr output to log as facility 'stderr'.
redirect_stderr: install it.
set_logger: new fun.
log: main interface.

- python prompt was confusing some readline commands
- save/restore readline history

This is an updated patch from pull request #16 which will throw an
exception if coro is called without starting the event_loop(). The
main update is to bring it up to date with recent changes and make
the linux poller throw the correct exception in this case.

flag readv() as not implemented.