* fix: apply automatic eslint fixes
* lint: allow hashbang comment for tiddlywiki.js
* lint: first back of manual lint fixes for unused vars
* lint: added more fixes for unused vars
* lint: missed files
* lint: updated eslint config with selected rules from #9669
* 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