* lib/rss/maker/taxonomy.rb: implemented taxonomy module for RSS
  Maker.
* lib/rss/taxonomy.rb: supported RSS Maker.
* lib/rss/maker.rb: added taxonomy module support.

* lib/rss/rss.rb: adjusted to other element API.
* lib/rss/1.0.rb: adjusted to other element API but backward
  compatibility is reserved.
* lib/rss/0.9.rb: ditto.

* test/rss/test_maker_taxo.rb: added test case for taxonomy module
  for RSS Maker.
* test/rss/test_setup_maker_1.0.rb: added tests for taxo:topic.

* test/rss/test_setup_maker_1.0.rb: added backward compatibility
  test.
* test/rss/test_setup_maker_0.9.rb: ditto.
* test/rss/test_setup_maker_2.0.rb: ditto.

* test/rss/rss-testcase.rb: added convenience method for setting
  up taxo:topic.
* test/rss/rss-assertions.rb: added assertion for taxo:topic.

* sample/rss/blend.rb: followed new API.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@10291 b2dd03c8-39d4-4d8f-98ff-823fe69b080e