* buffer.cc, buffer.h: (MoveDataHere) new method, optimize data copying by swapping buffers.
* FileCopy.cc: tune read delaying; add comments.
* DummyProto.cc, DummyProto.h, FileAccess.h, FileCopy.cc, Fish.cc,
Fish.h, Http.cc, Http.h, LocalAccess.cc, LocalAccess.h, SFtp.cc,
SFtp.h, example1.cc, example2.cc, ftpclass.cc, ftpclass.h:
change FA::Read to use Buffer and MoveDataHere.