Metadata extractor

Includes a README about metadata extraction using regexes, a brief shell script for trimming the converted HTML versions of PDFs, and extractor.html, which allows you to define extractors for bits of metadata and check results in a split-screen view.  filenames.json is an array of filenames (no extension), but the actual PDF and HTML files are not included.  In order for extractor.html to work, it would need a pdf/ and html/ subfolder with the relevant files as well.