Program control flow
-  New syntax  if ... else if ... else ...
-  XDG base directory conventions for configuration preferences are supported.
 The program reads initial commands from $XDG_CONFIG_HOME/gnuplot/gnuplotrc. Session command history is saved to $XDG_STATE_HOME/gnuplot_history. If these files are not found, $HOME/.gnuplot and $HOME/.gnuplot_history are used as in previous gnuplot versions.
-  unset warnings suppresses output of warning messages to stderr.
-  warn "message" prints filename, line number and message to stderr.
-  Exception handling for the "fit" command.  Control always returns to the
 next line of input, even in the case of fit errors.  On return, FIT_ERROR is non-zero if an error occurred. This allows scripted recovery from a bad fit. See fit error_recovery.