provide --no-fork command line option * octave.cc (no_fork_option): New static varaible. (NO_FORK_OPTION): New macro. (long_opts): Include it in the list. (usage_string, verbose_usage): Update for new --no-fork option. (octave_process_command_line): Handle NO_FORK_OPTION case. * octave-gui.h, octave-gui.cc (octave_start_gui): New arg, fork. Don't call dissociate_terminal if fork is false. * octave.h, octave.cc (octave_fork_gui): New function. * main.cc (main): Use it to pass --no-fork option to gui.