Update to 1.12.1

Update to 1.12.1

Changelog:

aria2 1.12.1
============

Release Note
------------

This release adds RFC 6249 Metalink/HTTP support. Current
implementation only uses rel=duplicate links.  --enable-direct-io
option was deprecated because of performance issue.  Since recent
GnuTLS uses libnettle as default instead of libgcrypt, this release
added initialization code for libgcrypt.

Changes
-------

 * Initialize libgcrypt.  We relied initialization of libgcrypt on
   gnutls_global_init(), but recent change in gnutls, which changes
   default crypto backend from libgcrypt to libnettle, leaves
   libgcrypt uninitialized if it uses libnettle as backend(and this is
   likely because libnettle is chosen by default). To fix this issue,
   we simply initialize libgcrypt on our own.

 * Throw exception with error message if gnutls_global_init() failed.

 * Implemented Metalink/HTTP.  Link header fields from first Metalink
   server is utilized as described in rfc6249. We only set digest from
   Digest header field to DownloadContext only when PieceStorage is
   not initialized(in other words, before file size is known). After
   PieceStorage is initialized, Digest header field is used to check
   the value is the same in digest in DownloadContext.  Current
   implementation only handles rel=duplicate.

 * Remove Metalink content-type after first server response.  We don't
   accept Metalink content-type after first server response.

 * Updated Russian translation of aria2 man page.  Thanks to ITriskTI
   for translation.

 * Fixed the bug due to dangling pointers in RequestGroup.
   RequestGroup holds a poitner to btRuntime_ and peerStorage_. After
   removing them from BtRegistry, we failed to set 0 to them.  When
   program access them, it goes undefined world, such as random crash.
   We found this bug when pasuing download and valgrind warned memory
   corruption.

 * Added log message to clarify error for BitTorrent server socket.

 * Added #deprecated help tag.

 * Removed deprecated options: --enable-xml-rpc, --xml-rpc-listen-all,
   --xml-rpc-listen-port, --xml-rpc-max-request-size, --xml-rpc-user,
   --xml-rpc-passwd.

 * Removed use of O_DIRECT because of performance issue.  Deprecated
   --enable-direct-io option.

 * Increased the maximum number of in-flight request in BitTorrent.

 * Added --log option to aria2rpc