* In the interests of performance and expressiveness, switched to using a Sax parser instead of a DOM implementation.
* Use extensible declarative rules to control the slicing process
* Added new optional set of rules for slicing by heading, where the paragraphs underneath a heading are packed into the same tiddler as the heading
* Added a modal dialogue for specifying parameters when slicing in the browser
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”.
