The exclude filter `+[tag[intro]]` will produce a document that only
includes the paragraphs with the tag “intro”. These are derived from
the paragraphs in the original document with the CSS class “intro”.
Now includes a special document view column on the left. Headings can
be expanded/collapsed, and tiddler titles can be inspected and renamed
via the toolbar. Clicking on an entry opens the associated tiddler. The
default tiddler view template includes a special section for tiddlers
that are part of a document
