Updating proj4js to 2.1.0

Sources: https://github.com/proj4js/proj4js/archive/2.0.1.zip
https://github.com/proj4js/proj4js/archive/2.0.2.zip
https://github.com/proj4js/proj4js/archive/2.0.3.zip
https://github.com/proj4js/proj4js/archive/2.1.0.zip

*.js files are min’d already, *-src.js non-min’d.

Addresses https://github.com/cdnjs/cdnjs/issues/2499