Bug fix. The structure for other data pipes was not been added in load_pdb().
Fix for load_pdb(). The structure needs to be loaded before displaying it.
Fixed the call to load_pdb().
Fix for the test_load_pdb() unit test.
Try that fix again!
Fix for the test_atom_loop_spin_selection2() unit test.
Fix for the atom_loop() method needed because of the load_pdb() changes.
Fixed some references to os.path.
Added the missing struct_index to load_pdb().