allow export and import of shortcut sets * settings-dialog.ui: new buttons for import/export of one of the shortcut sets * settings-dialog.cc (constrctor): bundle the code for the shortcut settings, connect slots to signals from the import/export-buttons; (im-/export_shortcut_set1/2): four new slots for the buttons signals * settings-dialog.h: new slots * shortcut-manager.cc (do_fill_treewidget): some code formatting; (do_write_shortcuts): set and settings as parameters, distinguish if all or only one set has to be written into the file; (import_shortcuts): new function for reading a shortcut set from a settings file; (do_import_export): new function called from the static wrapper function import_export for importing or exporting a shortcut sets; (enter_shortcut::enter_shortcut, enter_shortcut::handle_direct_shortcut, enter_shortcut::keyPressevent): added some comments * shortcut-manager.h (write_shortcuts): new parameters set and settings; (import_export): new static function; (do_write_shortcuts): new parameters set and settings; (do_import_export, import_shortcuts): new functions

To cite GNU Octave in publications use:

  John W. Eaton, David Bateman, Søren Hauberg, Rik Wehbring (2014).
  GNU Octave version 3.8.1 manual: a high-level interactive language for
  numerical computations.
  CreateSpace Independent Publishing Platform.  ISBN 1441413006,
  URL http://www.gnu.org/software/octave/doc/interpreter/

A BibTeX entry for LaTeX users is:

  @book{,
    author    = {John W. Eaton, David Bateman, S\oren Hauberg, and Rik Wehbring},
    title     = {{GNU Octave} version 3.8.1 manual: a high-level interactive language for numerical computations},
    publisher = {CreateSpace Independent Publishing Platform},
    year      = {2014},
    note      = {{ISBN} 1441413006},
    url       = {http://www.gnu.org/software/octave/doc/interpreter},
  }

We have invested a lot of time and effort in creating GNU Octave, please cite it
when using it.  See also `citation pkgname' for citing Octave packages.