relax SVN archive

The log() and tee() functions have been renamed to io_streams_log() and io_streams_tee(), and the
old IO.logging_off() class method has been converted to the io_streams_restore() function. The
io_streams_restore() function is also differently designed, using the true original IO streams
(sys.__stdin__, sys.__stdout__, and sys.__stderr__).

The IO.delete() method has been converted to a module function.

The IO class has been eliminated.