Log Message:
Update to version 0.13.1+2.  This update includes myriad bug fixes
and feature enhancements--way too many for this commit message.
While here, deprecate aria2-metalink option. Aria2 now supports
building with libexpat, so we do that by default now.

Some of the more significant changes:
-------------------------------------

* Fixed compile error without gnutls/libgcrypt/libgpg-error and openSSL
  installed.  Fixed compilation on: x84-64 platform, Mac OSX, g++-4.3,
  and without c-ares/ares.

* Added Simplified Chinese translation. Also updated the following
  translations: Polish, Dutch, German, Thai, Indonesian,
  Norwegian Nynorsk, Hungarian, Finnish, Hebrew.

* Changed inactive connection timeout to 120.
  To accept more mulually interested peers, disconnect peer when there
  is no interest between us after certain time passed.
  Lengthened DNS timeout to 30. I think old value '10' will be a
  little bit short when some DNS servers are offline and several
  DNS servers are tried. It should be configured by
  command-line option.

* Fixed the bug that prevents aria2 from stopping other than by pressing
  Ctrl-C in BitTorrent download. It is reproducible using --seed-time
  option. aria2 doesn't stop even after --seed-time is satisfied and
  continues to output blank lines in the console.

* Added Message Stream Encryption(MSE) support.
  Currently, aria2 accepts incoming connections with Obfuscation Header
  and legacy BitTorrent Header and establishes connections with
  Obfuscation Header first and if failed then retry with legacy
  BitTorrent header. If plain text and ARC4 is provided, aria2 always
  choose ARC4. The new option to change the default behavior is planned.
  For tracker extension, "supportcrypto=1" is added statically.

* Added the ability to load nodes from torrent file. These nodes are
  added to the routing table when downloading that torrent.

* Added the ability to stop aria2 itself when given time has passed
  from start. Use --stop option to specify time in minutes.
  When 0 is given, this feature is disabled.
  before calling RequestGroupMan::fillRequestGroupFromReserver().
  Without this modification, the result list shows "ERR" when aria2 is
  stopped by --stop option. It should be "INPR".
  Bootstrap through node added by port message.
  Currently bootstrap is executed if the number of buckets in routing
  table is 1.

* Added DHT functionality, compatible with mainline.
  DHT is disabled by default. To enable it, give --enable-dht to aria2c.
  You may need to specify entry point to DHT network using
  --dht-entry-point. DHT uses UDP port to listen incoming message.
  Use --dht-listen-port to specify port number. Make sure that your
  firewall configuration can pass through UDP traffic to the port.
  The routing table is saved in $HOME/.aria2/dht.dat.  Request peers though
  DHT only when download hasn't finished.