relax SVN archive

Added a module docstring.

Removed some no longer used RelaxError imports.

Removed junk code, left over from the copy from 'generic_fns/sequence.py'.

Modified the data model redesign document to show that the residue user function class is finished.

Fixed a typo in the docstrings of the unit tests for the generic_fns.residue functions.

Created the residue.display() user function.

This has been added to the data model redesign document. Two unit tests have also been created for
the function.

Created the residue.renumber() user function.

Added the residue.rename() user function.

Updated the docstring modifications of the 'residue' user function class.

Removed dud user functions from 'residue' which remained from the copy of 'sequence'.