Doxygen's svg.min.js script is composed of minified versions of the following
packages:
- svgdotjs           3.1.2: https://github.com/svgdotjs/svg.js
- svgpan-1.2mod.js     1.2: https://github.com/aleofreddi/svgpan

The Makefile will built the svg.min.js file used by doxygen.

Note that svgpan.js is heavily modified for use with doxygen,
so it cannot easily be upgraded to newer versions.
