A way to get next publisher confirm sequence number

[vincentjames501]

To do publisher confirms, it would be nice to have a next-publish-seq-no function in the langohr.channel ns. It would be awesome to brainstorm some additional ideas for #7 as I'm running into this now!

[michaelklishin]

All confirms-related functions are in langohr.confirm.

[vincentjames501]

Sure. I'm just commenting I think this function is missing and I have to make a native Java API call to Channel unless I'm missing something. I'd be happy to do a PR. I think this function could be useful for things other than just confirmations though which is why I suggested the other namespace though it doesn't matter much to me.