Reset the "must close" flag when we close the backend connection
before a retry.

Fixes #1494

Testcase by:	scoof
Also zap keep when purging.

Fixes #1139
Remove the stand-alone "purge" action from VCL, now that we have
return(purge) from vcl_recv.

Retain the VRT_purge() for VMOD and inline-C use.
Insert a newline before the actual panic message in order to
avoid line wrapping
Move a misplaced assert.

Fixes	#1478
Add documentation for the fallback director.
Rewrite first paragraph to make it easier to read.
Add dependeny to build both rst files from vcc.

Fix spotty dependency where none or just one of the
.rst files output by vmodtool.py was known by the Makefile.
Tiny lint; file is called vmod.vcc.
Output correct tool name.

And avoid hardcoding it, in case we change it in the future
some time.
Output autogen-msg to .rst; pythonify a bit.

Write a header in generated .rst files that it was generated from the
.vcc file.

Also softly sprinkled with some python formatting:
* use a python 2.5 context manager for the filepointer
* and make the output easier to read by avoiding concatination.
Remove text block dividers just added.

This made it easier to see where objects started/stopped, but
vmodtool.py don't believe in this comment format. Especially rst2man
wasn't impressed, so roll back for now.
Output RST comment with enough linefeeds.

Empty RST comments need an extra empty line afterwards, re this output
from rst2man:

    (WARNING/2) Explicit markup ends without a blank line; unexpected unindent
Halt rst2man/rst2html on warnings.

We don't allow compiler warnings in the C code, so I don't see any
reason why we should allow warnings in the documentation.

Warnings in the documentation are now build errors.
Delete unreferenced file vcl-intro.rst.

Sphinx complains that this file isn't referenced
anywhere, and a quick glance indicate that the contents
have been merged into other rst files.
Put vmod docs back into the documentation.

Squashing Sphinx warnings revealed that the vmod_std and
vmod_directors includes wasn't working.

Move the generated files a bit so Sphinx is happy to load them.

I'm not using include (where relative paths seem to work)
since that works differently in a TOC listing.
Increase Sphinx strictness.

Warnings are now considered build errors.

We've been shipping documentation with sections missing
because we didn't take warnings seriously.

Bonus change: build in parallel, save 82 centiseconds per build!
(html target on my laptop, ymmv)
Disable parallel build due to old sphinx.

The sphinx version on git.varnish-cache.org is v1.1.8 which
hasn't got -j.

In sphinx v1.2.2 (debian jessie) it is in place.

Guess we'll have to live with those extra 820 milliseconds
per build for now.
Remove remaining references to vcl-intro.rst.

These hard-code references were forgotten when I
removed this file in ebbd828.