Collapse two fetch states and make the X-Varnish heading for the backend
available in vcl_backend_fetch{}
Always release the req early if non-pass fetch, don't release it if
it is pass, we may beed the body for retries.
Serve ESI-includes from a different backend.

Serve ESI-includes from a different backend so that we don't race
against when the backend connection is ready for reuse.

Fixes: #1440
Regenerated from inline help. This should be automatic at some point.
Also, the inline help might be a bit more verbose.
First stab at a mostly syntax-oriented VCL manpage.
Feedback is welcome.
Forgot about microseconds and reals
Better error on missing import

Fixes: #1436
Also make IMS fetches possible in the interval ttl+grace and keep.
Fix IMS fetching of ESI objects.

Fixes #1442
Run-through of the first chapter in the docs

I'm happy with the first chapter for 4.0 release.
Add code to do the right "backwards" merge of IMS responses.
Add link to the man page
First stab at director documentation
remove the vcl vars from the index.
it is included in the vcl man page
req.backend is gone now. req.backend_hint is it.
Reuse the same beresp->obj function for both cond and normal fetches.
Make ESI a separate chapter
Move the content from cookies and vary into increasing perf
Update index, remove orphans, add esi
rebreak lines