yahns 1.6.0 - reduced allocations and bugfixes

This release fixes a bug where previously-configured-but-now-removed
listeners were inherited across USR2 upgrades are not shutdown
immediately in the child.

There are also minor reductions in allocations which can save a few
hundred bytes statically and also whenever write buffering is necessary
for large responses.

Some minor documentation updates improvements in extras, too.

shortlog of changes since 1.5.0:
      README: add link to mailing list archives
      test_ssl: factor out server SSLContext creation
      doc: add design_notes document
      reduce File::Stat object allocations
      update comments about wbuf_close return values
      wbuf: lazily (re)create temporary file
      fix compatibility with unicorn.git
      skip tests requiring String#b on 1.9.3
      use the monotonic clock under Ruby 2.1+
      favor Class.new for method-less classes
      extras/proxy_pass: save memory in String#split arg
      extras/proxy_pass: do not name unused variable
      extras/proxy_pass: log exceptions leading to 502
      extras/proxy_pass: flesh out upload support + tests
      acceptor: close inherited-but-unneeded sockets

See the git repository for more: git clone git://yhbt.net/yahns