Update readable names method for locales
Add license to qr.js and minify-protect licenses

If minification is used in the future, C-style /*! comments are often
recognized as keepers by many minifiers.
.gitignore/zip-exclude citeproc-js and locales

Revert to dir/* notation in .gitignore so subdirs with those names are
not excluded.

Exclude locales, citeproc-js from zip creation
Bundle citeproc-js and generate citations in-house

Not all citation styles are supported by citeref and datacite. Instead,
use their application/citeproc+json content type to retrieve citation
meta and generate the citation in the extension, using citeproc-js.
Update underscore.js to 1.7.0
Update QR generator

* Use new jQuery.qrcode
* Enable foreground and background color selection using Spectrum
  (version 1.5.1)
* Always use PNG image type
* Allow manual title insertion