Update p5-Text-Markdown from version 1.0.25 to version 1.0.29 (upstream
version 1.000029)

Pkgsrc changes:
- Adjust dependencies.
- Don't override Module::Install as extensions are bundled by upstream

Upstream changes:
1.0.29 2009-10-28T15:19:26
        - Note Test::Differences is needed for tests to run (RT#50918)
        - Change build_requires to test_requires in Makefile.PL where
          appropriate.

1.0.28 2009-10-27T14:28:12
        - Fix MANIFEST.skip to avoid extraneous crap in the distribution.

1.0.27 2009-10-25T19:13:47
        - Change to perl style version numbers (from 3 part versions) to
          avoid depndency confusion with Text::MultiMarkdown

1.0.26 2009-10-04T00:37:00
        - Minor POD changes (typos, wrapping)
        - Added note about and test for output always ending in exactly one newline (dandv)
        - Fix RT#48943 + tests (genehack)
        - Support for optionally interpreting markdown in HTML block elements
          using the markdown="1" attribute (GitHub issue #1; dandv)

(seb)