relax SVN archive

Added 2 unit tests for the new args of the structure.read_pdb() user function.

Added a missing RelaxError import.

Fixed the test_read_pdb_argfail_load_seq() unit test.

Fixed all the 'structure' user functions to use the new package.

Converted the 'structure' package into a subpackage of 'generic_fns'.

This solves a module import issue, and is a logical place for the code.

Added the 'geometric' module to the __all__ list.

Fixed the import of the structure package.

Shifted all the functions relating to geometric objects into structure.generic.

Corrected a few errors created while changing the code to the new design.

These were noticed by Edward d'Auvergne in a post at:
https://mail.gna.org/public/relax-devel/2008-04/msg00028.html (# Message-id:
<7f080ed10804040040v3fdeb265p959479026923d71a@...>)

Modifications to the structure.read_pdb() user function.

The 'parser' argument has been added to allow different PDB parsers to be selected in the future.
To allow for the new relax design, the docstring has been updated with respect to the loading of the
sequence and the 'spin_id' argument has been added to allow the selection of specific atoms of the
PDB file to be placed as SpinContainers in the relax data store.