aria2/TODO

* Add HTTP POST support
* Add expires handling for Cookie
* Add SSL server cert verification
* Add SSL client cert support
* Better HTTP status handling
* Add the feature which adds or removes URLs on-the-fly.
* Add port range command-line option
* Add max peers command-line option
* Refacturing HttpConnection and FtpConnection
* Query resource by location
* List available os, version, etc for metalink
* ipv6(RFC2428 for ftp)
* Add silent mode.
* Save URLs and command-line arguments to .aria2 file.
* Add a control port for GUI frontend
* Use SharedHandle where it is useful.
* Rewrite Util::countBit
* Add --bt-timeout command line option.
* remove blockIndex
* Add seed mode.
* consider life cycle of requestGroup and segmentMan
* exit status: all downloads have been successful-> EXIT_SUCCESS,
		some of downloads have been failed -> EXIT_FAILURE

* Fix log and stdout message in Metalink related class.
* Fix Cookie header's value. ';' is not necessary at the end of it.
* Time::getTimeInMillis() returns int64_t.
* Util::secfmt, What happens if sec is less than 0?
* Rewrite ChunkedEncoding
* typedef int32_t CUID in common.h or a2types.h

* io related headers and compatible macros and definition -> a2io.h
* net related headers and compatible macros and definition -> a2netcompat.h
* time related headers and compatible macros and definition -> a2time.h
* used globally -> common.h

* Add pgp verification support. I have to use libgpgme??

* Rewrite following classes using TimeBasedCommand
	src/ActivePeerConnectionCommand.h
	src/FillRequestGroupCommand.h
	src/HaveEraseCommand.h
	src/PeerChokeCommand.h
	src/TorrentAutoSaveCommand.h
* Rewrite MetaFileUtil
* Reconsider the use of RecoverableException and FatalException
* Limit the number of opening file to,say,100 in MultiDiskAdaptor.
* Implement the feature to treat http/ftp as auxuality download method for BitTorrent
* http-seeding(single and multi-file torrent)
* Use content-type for PostDownloadHandler
* Rewrite exception usage:
  RecoverableException
    DlRetryEx .... Retry using same connection/url. Should be renamed to TemporaryFailureException
    DlAbortEx .... Abort download with the connection/url. Should be renamed to PermanentFailureException
    DownloadFailureException .... RequestGroup should halt.
  FatalException .... Program should abort.

-- remaining features to be implemented for 0.12.0 release
* Reimplement ChecksumCommand(validation using 1 checksum for 1 file)
* Implement duplicate download checking in Bt
* improve --metalink-location field
* Piece length conversion when loading file