A number of changes made while trying to reproduce #176:

A number of changes made while trying to reproduce #176:

 - modify thread_log() to take an "errcode" argument (typically errno) so
   we don't have to sprinkle the code with strerror() calls.

 - read_line() and read_block() would sometimes unnecessarily log an error
   for a short read; let the caller decide whether a short read is
   acceptable.

 - reorder the if / else if / else blocks in receive_response() so the
   logic is easier to follow.

 - remove test code which we no longer need.

 - fix some style issues; there are still a couple of long lines, though.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@2501 d4fa192b-c00b-0410-8231-f00ffab90ce4