Remove the onm.Backchannel object constructor from onm module.exports...
... The backchannel pattern is useful, potentially, in client code but really doesn't belong as part of onm itself. I may bring it back in some form as a test fixture. But, never as a module export for clients who should roll their own solution. Or, use a re-usable package. Just not onm.
File renaming.
Take out dated comments.