clean up memory allocated for singletons before exit * singleton-cleanup.h, singleton-cleanup.cc: New files. * liboctave/Makefile.am (INCS, LIBOCTAVE_CXX_SOURCES): Add them to the lists. * toplev.cc (clean_up_and_exit): Call singleton_cleanup_list::cleanup. * debug.h, debug.cc (bp_table::instance_ok): Move definition to debug.cc. * coment-list.h (octave_comment_buffer::~octave_comment_buffer): Define destructor for class. * ov-typeinfo.h (octave_value_typeinfo::~octave_value_typeinfo): Likewise. * cmd-edit.h (command_editor::cleanup_instance): New function. * cmd-hist.h (command_history::cleanup_instance): New function. * file-ops.h (file_ops::cleanup_instance): New function. * mach-info.h (oct_mach_info::cleanup_instance): New function. * oct-env.h (octave_env::cleanup_instance): New function. * oct-fftw.h (octave_fftw_planner::cleanup_instance): New function. * oct-rand.h (octave_rand::cleanup_instance): New function. * oct-spparms.h (octave_sparse_params::cleanup_instance): New function. * pathsearch.h (static_members::cleanup_instance): New function. * comment-list.h (octave_comment_buffer::cleanup_instance): New function. * debug.h (bp_table::cleanup_instance): New function. * display.h (display_info::cleanup_instance): New function. * dynamic-ld.cc (octave_shlib_list::cleanup_instance, octave_mex_file_list::cleanup_instance): New functions. * dynamic-ld.h (octave_dynamic_loader::cleanup_instance): New function. * load-path.h (load_path::cleanup_instance): New function. * oct-stream.h (octave_stream_list::cleanup_instance): New function. * ov-typeinfo.h (octave_value_typeinfo::cleanup_instance): New function. * pager.h, pager.cc (octave_pager_stream::instance_ok, octave_pager_stream::cleanup_instance): New functions. (octave_diary_stream::instance_ok, octave_diary_stream::cleanup_instance): New functions. * sighandlers.h (octave_child_list::cleanup_instance): New function. * toplev.h (octave_call_stack * pager.cc (octave_pager_stream::stream, octave_diary_stream::stream): Use instance_ok to create instance. * toplev.h (octave_call_stack::cleanup_instance): New function. * cmd-edit.cc (command_editor::instance_ok): Register cleanup function. * cmd-hist.cc (command_history::instance_ok): Likewise. * file-ops.cc (file_ops::instance_ok): Likewise. * mach-info.cc (oct_mach_info::instance_ok): Likewise. * oct-env.cc (octave_env::instance_ok): Likewise. * oct-fftw.cc (octave_fftw_planner::instance_ok): Likewise. * oct-rand.cc (octave_rand::instance_ok): Likewise. * oct-spparms.cc (octave_sparse_params::instance_ok): Likewise. * pathsearch.cc (dir_path::static_members::instance_ok): Likewise. * comment-list.cc (comment_list::instance_ok): Likewise. * debug.cc (bp_table::instance_ok): Likewise. * display.cc (display_info::instance_ok): Likewise. * dynamic-ld.cc (octave_shlib_list::instance_ok, octave_mex_file_list::instance_ok, octave_dynamic_loader): Likewise. * load-path.cc (load_path::instance_ok): Likewise. * oct-stream.cc (octave_stream_list::instance_ok): Likewise. * ov-typeinfo.cc (octave_value_typeinfo::instance_ok): Likewise. * sighandlers.cc (octave_child_list::instance_ok): Likewise. * symtab.h, symtab.cc (symbol_table::scope_id::create_instance): New function. * symtab.h (symbol_table::scope_id::instance_ok): Call create_instance. * toplev.h, toplev.cc (octave_call_stack::create_instance): New function. * toplev.cc (octave_call_stack::instance_ok): Call create_instance. * pager.h, pager.cc (octave_pager_stream::set_diary_skip, octave_pager_stream::flush_current_contents_to_diary): Now static. octave_pager_stream::do_set_diary_skip, octave_pager_stream::do_flush_current_contents_to_diary): New functions. (octave_pager_stream::stream): Return std::ostream&, not octave_pager_stream&. If instance creation fails, return std::cout. (octave_diary_stream::stream): Return std::ostream&, not octave_diary_stream&. If instance creation fails, return std::cout. (octave_pager_stream::do_reset, octave_diary_stream::do_reset): Use instance_ok to create instance.