relax SVN archive

Converted the open_write_file class method into a module function.

Converted the open_read_file class method to a function.

Converted the log class method to a function.

Added a simple docstring to the relax_io module.

Fix for the renaming of io.py to relax_io.py.

The module renaming has been taken into account as well as the eventual removal of the IO class and
the conversion from class methods to module functions.

Added some comments for the import statements.

The open_read_file function is now imported as well.

Modified the unit tests for generic_fns.state to import from relax_io.

The function open_write_file is now imported (although it doesn't currently exist).

Renamed the relax io module to relax_io as it clashes with the Python io module.

Removed the old State class from the namespace of 'self.relax.generic'.