improve naming of debug pointer update callbacks and signals * file-editor-interface.h (file_editor_interface::handle_update_debug_pointer_request): Rename from file_editor_interface::handle_dbstop_request. Change all uses. * file-editor.h, file-editor.cc (file_editor::handle_update_debug_pointer_request): Rename from file_editor::handle_dbstop_request. Change all uses. * main-window.h, main-window.cc (main_window::handle_update_debug_pointer_request): Rename from main_window::handle_dbstop_request. Change all uses. * octave-event-listener.h (event_listener::update_debug_pointer): Rename from event_listener::dbstop. Change all uses. * octave-link.h, octave-link.cc (octave_link::do_update_debug_pointer): Rename from octave_link::do_dbstop. Change all uses. (octave_link::do_debug_input_event_hook_fcn): Rename from octave_link::do_dbstop_event_hook_fcn. Change all uses. * octave-main-thread.cc (debug_input_event_hook_fcn): Rename from dbstop_event_hook_fcn. * octave-qt-event-listener.h, octave-qt-event-listener.cc (octave_qt_event_listener::update_debug_pointer): Rename from octave_qt_event_listener::dbstop. Change all uses. (octave_qt_event_listener::update_debug_pointer_signal): Rename from octave_qt_event_listener::dbstop_signal. * input.cc (debug_input_event_hook_functions): Rename from dbstop_event_hook_functions. Change all uses. (Fadd_debug_input_event_hook): Rename from Fadd_dbstop_event_hook. Change all uses. (Fremove_debug_input_event_hook): Rename from remove_dbstop_event_hook. Change all uses.