first implementation of a shortcut manager (bug #41217) * file-editor.cc (set_shortcuts): use shortcut-manager to set some shortcuts * main_window.cc (set_global_shortcuts): use shortcut-manager to set some shortcuts; (construct_file_menu): all actions as class variables; (construct_edit_menu): all actions as class variables; * main_window.h: actions as class variables * module.mk: new files shortcut_manager.cc, shortcut_manager.h * octave-gui.cc (octave_start_gui): initialize the shortcut_manager * settings-dialog.cc (constructor): call shortcut-manager for shortcut table (write_changed_settings): call shortcut-manager for writing shortcuts * settings-dialog.ui: new tab with a tree widget for the shortcuts * shortcut_manager.cc (constructor, destructor): new class; (instance_ok): checks if instance is valid, creates a new one otherwise; (do_init_data): initialize the list with all shortcut's data; (init): internal function for initializing the data list; (do_fill_treewidget): fills the tree widget in the settings dialog; (do_write_shortcuts): writes shortcuts from settings dialog into file; (do_set_shortcut): setting the shortcut for an action; (handle_double_clicked): slot for double clicking into the tree widget; (shortcut_dialog): dialog for entering a new shortcut; (shortcut_dialog_finished): processing the dialog's result; (shortcut_dialog_set_default): setting the shortcut to it's default; (enter_shortcut::enter_shortcut): new class derived from QLineEdit; (enter_shortcut::handle_direct_shortcut): switch between normal editing and directly entering a shortcut; (enter_shortcut::keyPressEvent): event handler filtering the shortcuts; * shortcut_manager.h (init_data): static function calling do_init_data; (write_shortcuts): static function calling do_write_shortcuts; (fill_treewidget): static function calling do_fill_treewidget; (set_shortcut): static function calling do_set_shortcut;

Summary of important user-visible changes for version 4.0:
---------------------------------------------------------

 ** For compatibility with Matlab, the "backtrace" warning option is now
    enabled by default.

 ** The preference

      do_braindead_shortcircuit_evaluation

    is now enabled by default.

 ** The preference

      allow_noninteger_range_as_index

    is now enabled by default and the warning ID

      Octave:noninteger-range-as-index

    is now set to "on" by default instead of "error" by default and "on"
    for --traditional.

 ** polyeig now returns a row vector of eigenvalues rather than a matrix
    with the eigenvalues on the diagonal.  This change was made for Matlab
    compatibility.

 ** Other new functions added in 4.0.0:

    validateattributes

 ** Deprecated functions.

    The following functions were deprecated in Octave 3.6 and have been
    removed from Octave 4.0.
                                           
      cut                polyderiv        
      cor                shell_cmd        
      corrcoef           studentize       
      __error_text__     sylvester_matrix 
      error_text         

    The following functions have been deprecated in Octave 4.0 and will
    be removed from Octave 4.4 (or whatever version is the second major
    release after 4.0):

      allow_noninteger_range_as_index
      do_braindead_shortcircuit_evaluation

---------------------------------------------------------

See NEWS.3 for old news.