Fixed bug where rule IDs wouldn't get incremented
Added tag filtering

* Tags are now scanned for keywords
* Whole-word scans now use a hashtag-friendly regex
Style link descriptions properly
Added loading spinning icon to footer
Fixed a Read More bug where inline nodes showed up

In a scenario like <p>[[MORE]] I <em>knew</em> it!</p>, only the text node
" I " would be hidden. Element nodes are now handled sanely.