Tokio support

[polachok]

I started working on tokio support here: https://github.com/polachok/pnetlink/tree/tokio

[maufl]

I need this, I started to implement it myself before I found your implementation. Can I help you with this?

[bkchr]

@maufl if you bring this into a workable state, I would merge your changes!

[maufl]

Could you maybe give me some pointers what is not yet working?

[bkchr]

I never tried the tokio branch, but the commit messages sound really like "it works, but nothing more". Is the branch working for you and deliver everything you require?
I would think that there is some stuff missing and can also be improved.

[maufl]

Ok, I'll get started on it as soon as I'm done with rust-igd :)

[maufl]

I'm sorry but I currently neither have the time nor the need anymore to implement this. :( I wrote a minimal implementation that just notifies me on route changes which is enough to detect network changes.

[sp3d]

I'm working on PR #38 to try to move this forward. Comments appreciated.

[sp3d]

Basic Tokio support landed in #39, but the ergonomics of the lib for Tokio are still not great (iterators on NetlinkConnection don't interact well).