Some applications make multiple subscriptions to the same app on the
same path. Support this by changing the subscription interface to return
a numeric reference which needs to be passed in during the explicit
unsubscribe, and ensure that we send per-subscription instead of
per-path unsubscribe commands to Gall.
* lighter-than-eyre:
Actually have a 400 Bad Request page instead of reusing the 500 page incorrectly.
Changed the generator interface so a generator can redirect and set headers.
can't wake up
A %coup failure from gall should return a 500 to the client.
* lighter-than-eyre:
Actually scry for the +code and inject the code deterministically into the tests
Having the client unsubscribe should actually unsubscribe on the server
Instead of continuing to struggle with all the places in arvo where we
assume that vane names are one letter and that one letter is the first
letter of the full vane name, just use %l/lient and %r/rver for now to
finish the split of %light into a separate http client and server vane.
