Added direct I/O support. The current implementation uses O_DIRECT,
which is not posix standard and is tested on linux 2.6.21.
Currently only file allocation uses direct I/O.
* src/SingleFileAllocationIterator.{h, cc}
* test/SingleFileAllocationIteratorTest.cc
* src/MultiFileAllocationIterator.{h, cc}
* test/MultiFileAllocationIteratorTest.cc
* src/BinaryStream.h
* src/DiskWriter.h
* src/AbstractDiskWriter.{h, cc}
* src/ByteArrayDiskWriter.h
* src/DiskAdaptor.h
* src/AbstractSingleDiskAdaptor.{h, cc}
* src/MultiDiskAdaptor.{h, cc}
* src/FileAllocationEntry.cc
* src/Util.{h, cc}
* src/OptionHandlerFactory.cc
* src/prefs.h
* src/version_usage.cc
* src/option_processing.cc
Moved FileAllocationMan::markCurrentFileAllocationEntryDone() to
handleException.
* src/MultiFileAllocationIterator.cc
Added EINTR handling
* src/SocketCore.cc
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.