debugrevspec: deprecate --optimize option This option has been superseded by '--show-stage NAME', and will cause confusion in future patches.

debugrevspec: add option to print parsed tree at given stages "-p <stage>" is useful for investigating parsing stages. With -p option, a transformed tree is printed no matter if it is changed or not, which allows us to know valid stage names by "-p all".

debugrevspec: transform and print parsed tree by stages Prepares for adding new option to print transformed tree at each stage.