relax SVN archive

Fixes for all the unit tests of the Selection.contains_res() method.

Wrote 3 unit tests for the Scientific_data.__residue_loop() method.

Fixes for the __residue_loop() method.

The selection object is now used for comparison.

Implemented the Selection.contains_res() method.

Added another unit test of the Selection.contains_res() method.

Wrote 6 unit tests for the currently non-existent Selection.contains_res() method.

Fix for the Scientific_data.__molecule_loop() method.

The Selection.contains_mol() method is being used to identify matching molecules.

Fix for the Selection.contains_mol() method.

If the molecule name is None and there are no molecules in the selection object, the function
returns True.

Bug fix for the Selection.contains_mol() method. The recursive call was misspelt.

Fix for Selection.contains_mol(). The mol arg is now a keyword arg which defaults to None.