Channelfinder api v1

[jacomago]

I think I posted this somewhere at some point, but maybe I forgot.

Here is my design I did last year:

https://gist.github.com/jacomago/a82cf603d9de696322d289abc8f36e5f

I think the new thoughts from

#53
and #222

should go into this.

[jacomago]

Oops, I used the old design, updated for the new one.