Make the #gconf.large_file_chunk_size value be configurable
Add support of many options for tcp/ssl sockets

By adding a "<listen_opts> ... </listen_opts>" block in vhosts
configuration, it is possible to define some options to be set on listen
sockets and, by inheritance, on accepted sockets. Supported options are
(see inet:setopts for details):

  * buffer
  * delay_send
  * linger
  * nodelay
  * priority
  * sndbuf
  * recbuf
  * send_timeout
  * send_timeout_close

send_timeout / send_timeout_close options could be very useful to handle
unresponsive clients and thus avoid some sorts of DoS.