relax SVN archive

Wrote the identification string documentation.

This documentation is the string 'generic_fns.selection.id_string_doc'. The residue.delete() user
function docstring has had this string added to the end.

Updated the data model redesign document.

The spin_loop() generator function and selection syntax parsing functions tokenise() and
parse_token() are now implemented.

Wrote the generic_fns.selection.parse_token() function and 13 unit tests covering the function!

The unit tests attempt to cover all proper and improper combinations of the supplied token including
numbers (integers), names, and number ranges.

Wrote the generic_fns.selection.tokenise() function and 28 unit tests covering the function!

The unit tests attempt to cover all proper and improper combinations of the selection string.

Small bug fix for the test_residue_loop_no_selection() unit test.

Implemented the generic_fns.selection.residue_loop() generator function.

Bug fix.

The spin_loop() and molecule_loop() generator functions now accept zero arguments for the selection
of everything. This fixes two of the unit tests. The test_molecule_loop_no_selection() unit test
has also been fixed.

Multiple unit tests for the spin_loop(), residue_loop(), and molecule_loop() generator functions.

These generator functions belong to the 'generic_fns.selection' module.

Created the RelaxMolSelectDisallowError and RelaxResSelectDisallowError errors.

Wrote the molecule_loop() generator function for looping over and returning molecule containers.

The full generator function is generic_fns.selection.molecule_loop().