Use the new matching algorithm for anchoring text quote selectors. This
is faster than the existing one when many quote selectors fail to exactly match
and gives us more insight into and control over the fuzzy matching
process.

 - Use the `matchQuote` function to do find the best match for the quote
   in the text, replacing the `dom-anchor-text-quote` library.

   This resolves a problem where the browser could become unresponsive
   for a significant period of time when anchoring large numbers of
   annotations (hundreds) on pages where there have been significant
   changes in the content.

   In the "Public" group on http://www.americanyawp.com/text/01-the-new-world/
   for example the client spends a total of ~2.4 seconds running JS in between starting
   the client and anchoring completing compared to ~11 seconds with the
   previous implementation.

   The new implementation also provides more control over the degree of
   mismatch between quote selector and document text that is allowed.
   The current settings provide higher recall (larger proportion of
   "correct" approximate matches found) than the previous
   implementation. On http://www.americanyawp.com/text/01-the-new-world/
   for example the number of orphans dropped from 137 to 63.

   Finally the new library is also smaller. The minified `annotator.bundle.js`
   size is reduced by 15% (25KB).

 - Change `TextQuoteAnchor.fromSelector(...)` to generate the selector
   directly rather than delegating to `dom-anchor-text-quote`. This
   gives us more control over how quote selectors are generated and more
   easily change factors such as the amount of context included.