relax SVN archive

Implemented the generic_fns.structure.pdb_read.helix() function.

Completed the unit test of the generic_fns.structure.pdb_read.helix() function.

Added some more unit tests for the generic_fns.structure.pdb_read module.

These tests are not yet complete, as it is unknown what these unimplemented functions will return.

Faster PDB parsing by the removal of the use of the re.search() function.

Now line slices are directly compared instead.

Added a series of _parse_pdb_*() methods to the internal structural object.

These correspond to each section of the PDB format version 3.30
http://www.wwpdb.org/documentation/format33/v3.3.html. The currently loop over the records of their
section, returning the remaining PDB records. The aim is for fast parsing and breaking into
sections.

Better checks for the atomic data in the Structure.test_read_pdb_1UBQ system test.

Created the Structure.test_read_pdb_1UBQ to check the complete parsing of the complex PDB file.

The test is currently quite basic and needs to check more of the internal structural object.

Changes to the internal structural object.

The _parse_models_pdb() method has been renamed to _parse_pdb_coord() and the opening of the PDB
file shifted into the base load_pdb() method. This is in preparation for better parsing of PDB
files to match the main sections of the PDB format, see
http://www.wwpdb.org/documentation/format33/v3.3.html.

Added the full 1UBQ PDB structure to the relax test-suite shared data directories.

This is a small, very quick to read structure which will be used for validating the reading and
writing of different PDB record types.

Fix for the unit tests of the generic_fns.structure package.

The _parse_pdb_record() is now covered by the new pdb_read module, so its unit tests have also been
shifted into a new module.