Implemented BitTorrent/http/ftp integrated download.
I've rewritten lots of files and now some headers have forward
class declarations to reduce compile time.
The implementation is extremely alpha stage, I recommend to use this
for testing purpose only.
Automatically save *.aria2 control file of http/ftp download in
every
60 seconds.
* src/AutoSaveCommand.{h, cc}: New class.
* src/TimeBasedCommand.{h, cc}: New class.
* src/DownloadEngineFactory.cc (newConsoleEngine)