connection.

Highlights:

* Improved buffer handling. A vtx can now have a mix of buffered and
  shm chunks. And as shm refs are used and later buffered, they can be
  reused on the same vtx. This benefits long running transactions.

* Synth records are now returned by the cursor at the position the
  cursor was at when it was created. This solves a problem when
  writing to a file and a vtx times out, the reading of that file
  would also cause a time out delay.

* Begin records are now strictly honored, and any records before a
  Begin record are now ignored.

* More asserts on the structures

* More comments, should be easier to understand now

* Various other changes

Log a little bit more debugging information for now.

In general new/changed/killed objects are posted in the exp_thread
mailbox, and suitably handled by the exp_thread at its convenience.

The binheap is only manipulated by exp_thread, and it doesn't
need to hold any locks to do so.

The exp_mtx only protects the inbox to the exp_thread.

oc->flags and the lru-list are protected by the lru->mtx.

EXP_NukeLRU() is temporarily disabled.

When LRU-Nuking to make space, we mark the object as dying, so HSH
will ignore it and steal the storage from it right away.  We post the
rest of the object to exp_thread to clean up later.

The LRU change makes the 3-4 LRU test-cases unstable, (c00044, c00045,
r01140...) because they were used to the full object being reaped,
rather than only the storage segments.  I'm to tired to fix/tune those
cases tonight.

But apart from that, it seems to run the test-cases.

This should make object creation faster.

As a sideeffect, we loose the $expiry_sleep parameter:  Now we always
sleep optimally.

multiple instances at a later date.

Put the "LRU_DONTMOVE" flag on the lru, rather than the objcore.

32 and 64 bit architectures.

The good news is that this is necessary because our obj overhead
decreases.

to check:  The req might get rescheduled before we get there.

We now kill objects when t_origin + ttl + grace + keep has elapsed.

Losse EXP_Grace() and EXP_Keep() functions

Kill req.keep (it never made any sense in the first place).

Make sure to flush the file stream on exit in VUT

Left over code in VUT_main was preventing Ctrl-C handling when looping
trying to reconnect. Remove offending code.

object was created, as best we can determine it from the headers etc.

This is also the point from which ttls should be counted.

clear req->wrk on a busy-waiting request.

time-math one place.

Federico's taste :-)

Reset vfp when restarting in deliver, in case it has be set in
cnt_fetchbody already.

Fixes: #979

Conflicts:
	bin/varnishd/cache_center.c

Spotted by: Coverity

Spotted by: Coverity