[WIP] Add ws connector interface

(partially) targets #160 

This is what I figured from the specs.
I admit I'm not completely sure how this thing is gonna work (especially the flushing / the actual data transfer via outbuf).
But I wanted to do this in order to gain a better understanding of how stuff works, so I hope that's still alright...

I'm thankful for corrections and/or hints about which prototypes are still missing.
The include for the header is missing here.