check object size before plotting from variiable editor (bug #56685) * variable-editor-model.h: make data_rows and data_columns public * variable-editor.cc: do not include QSignalMapper here; (idx_to_expr): remove obsolete static function; (make_plot_mapper): only add the plot command to the mapper; (selected_to_octave): remove obsolete function; (selected_command_requested): get selected range and the object size from the model for comparing object size and selection, generate command string and emit signal for executing it in the console; (createVariable): only pass keywoard for variable creation instead of complete complete, which is now generate in selected_command_requested; (variable_editor): initialize new class variable for the edtiors plot signal mapper; (edit_variable): connect signal mapper to selected_command_requested and remove connection from previously used relay signal; (relay_selected_command): removed, direct connection is used; (construct_tool_bar): create plot mapper and store it for later connecting its signal, remove connection here * variable-editor.h: include QSignalMapper here; removed selected_to_octave; removed selected_command_signal; removed relay_selected_command; added class variable m_plot_mapper;