** an error message and quit.
**
** Exception: if "--" is encountered, it is consumed from the argument
** list and this function immediately returns. The effect is to treat
** all arguments after "--" as non-flags (conventionally used to
** enable passing-in of filenames which start with a dash).
**
** This function must only be called one time per app invokation.
** Calling it more than once results in undefined behaviour.
** This function must normally only be called one time per app
** invokation. The exception is commands which process their
** arguments, call this to confirm that there are no extraneous flags,
** then modify the arguments list for forwarding to another
** (sub)command (which itself will call this to confirm its own
** arguments).
*/
void verify_all_options(void){
  int i;
  for(i=1; i<g.argc; i++){
    const char * arg = g.argv[i];
    if( arg[0]=='-' ){
      if( arg[1]=='-' && arg[2]==0 ){