Log Message:
Update to 2.51

Upstream changes:
2.51   - fixed rt.cpan.org#77667 which resulted in invalid configs
          written to file when using save_file() and a named block,
          whose 2nd part starts with a /.

        - fixed rt.cpan.org#64169 by applying patch by Dulaunoy Fabrice.
          adds -NoEscape switch which turns off escaping of anything.

        - implemented suggestion of rt.cpan.org#67564 by adding 3 new
          parameters: -NormalizeOption, -NormalizeBlock and -NormalizeValue,
          which take a subroutine reference and change the block,
          option or value accordingly.

        - fixed rt.cpan.org#65860+76953 undefined value error.