address comment of Tobias regarding a75bbdf7

modules/base/src/invalid_handle.hh

modules/img/base/tests/test_image.cc

modules/mol/base/pymod/export_atom.cc

modules/mol/base/pymod/export_chain.cc

modules/mol/base/pymod/export_entity.cc

modules/mol/base/pymod/export_residue.cc

modules/mol/base/src/atom_base.hh

modules/mol/base/src/atom_handle.hh

modules/mol/base/src/chain_base.hh

modules/mol/base/src/chain_handle.hh

modules/mol/base/src/entity_base.hh

modules/mol/base/src/entity_handle.hh

modules/mol/base/src/residue_base.hh

modules/mol/base/src/residue_handle.hh

modules/mol/base/tests/CMakeLists.txt

modules/mol/base/tests/test_chain.cc

modules/mol/base/tests/test_entity.cc

modules/mol/base/tests/test_residue.cc

modules/mol/base/tests/test_surface.cc

modules/seq/base/tests/test_alignment.cc