Handle the next option, found during pass 1.
The parser calls this virtual methode each time an option was found during the first pass of a two pass argument parsing.
The two pass parsing operation is helpfull to handle complex option argument dependencies. In the most cases this methode is NOT reimplemented by the derived class.
Example: The argument layout of option '-x <...>' might depend on the existence of option '-g'. That means, if the '-g' option is given, the argument of '-x <...>' is '<entryname>,<entryvalue>'. In the other case the argument has to be '<entryname>'. Since the option sequence is unrestricted the '-g' option must be detected during the first pass to handle the argument of option '-x' correctly during pass two.