editor with smart indentation for octave files (bug #41554) * file-editor-tab.cc (file-editor-tab.cc): new class variables for line, column, changed lines and auto-indent setting, connect signal linesChanged to new slot; (notice_settings): get setting for auto-indent and store it in flag; (handle_lines_changed): new slot for changed lines, just storing this state in a flag; (handle_cursor_moved): if lines have changed check more conditions and call smart indentation; (do_smart_indent): do the smart indentation based on keyword in previous line * file-editor-tab.h: new class variables, new slot for chaned lines, new method for smart indentation

gnulib-hg = gnulib-hg