add fs::Session::read()
	modified:   ftp/session.cpp <--working on
move usertable  to server class  as shared data
	modified:   ftp/server.hpp
	modified:   ftp/session.hpp
change user table as shared among threads
	modified:   ftp/server.cpp
	modified:   ftp/session.cpp
	modified:   ftp/session.hpp
set stop mark
	modified:   ftp/session.cpp
mark stop point
	modified:   ftp/session.cpp
	modified:   ftp/session.hpp
fix parsing bug added operator == !=
	modified:   ftp/command.hpp
update