Initial taxonomy implementation. There's still a ways to go -- I totally punted on depth -- and we need a few more argument handlers.

Add basic support for summary styles; they don't quite work yet because view URL knowledge isn't implemented.

#188640 (by Crell): Add default views, and lots of comments, many of which need to be dealt with one way or another.

Very early checking for Views 2 for Drupal 6. Currently query.inc looks good and view.inc can at least load and save views, though the schema needs more tweaks.