Fix a bug caused by latency with changing document length.
Extract reusable logic out of ErrorTagger into a base Tagger.
Simplify finding spans to invalidate.
New Classification Tagger based on Highlight information from Analysis Service.
Removed old regex-based classifications.
No idea what these changes are; GH4W won't show them...

GH4W shows "Binary files differ", though I'm pretty sure there are no
changes in them.