+ - shogi_server/command.rb:
+ + For an unknown error command log, an empty line is no longer logged.
+ + Commands specific to 81Dojo, starting with '%%%', are just
+ ignored instead of unknown command errors.
+ - shogi_server.rb:
+ + Refactoring. Added test/TC_logger.rb to test
+ ShogiServer::Logger class.
+ + Fixed race condition: creating a new directory to archive
+ logs may have caused race condition, which ended up with
+ making the server unavailable. This issue has been fixed.