refactor renumber.Renumber

modules/mol/base/pymod/export_editors.cc

modules/mol/base/pymod/export_residue.cc

modules/mol/base/src/editor_base.cc

modules/mol/base/src/editor_base.hh

modules/mol/base/src/impl/chain_impl.cc

modules/mol/base/src/impl/chain_impl.hh

modules/mol/base/src/residue_prop.hh

modules/seq/alg/pymod/renumber.py

modules/seq/alg/tests/test_renumber.py

modules/seq/base/src/sequence_handle.hh