Improve xpath highlight mismatch searching

[techgique]

If the highlight text identified by the xpath element and range don't match the annotation quote, we search the xpath element for the quote verbatim. We might be able to save time manually handling when the quote can't be found verbatim by:

• Looking for only the first word (or couple words) in the annotation quote when searching for the whole string returns no matches
• Stripping XML markup that won't exist in the annotation quote (because it is removed from the HTML in the TEI Boilerplate page) before performing the search