IE8 support dropped

Support for IE8 dropped (in the form of no longer being able to generate PNG fallbacks for inline SVGs). No only should nobody be supporting a ten year old browser any more, but this lets the total dependencies shrink by nearly 300MB as they don't need to include a SVG->PNG converter anymore.

Also fix a bug that was causing duplicate IDs.

2.0.3

• Update dependencies
• Remove repreciated "new Buffer()" use

2.0.2

• Updated dev dependencies to fix a lodash prototype pollution warning.

2.0.1

• Updated "convert-svg-to-png" dependency from 0.4.0 to 0.5.0

v2.0.0

• Updated Gulp dependency to Gulp 4 instead of Gulp 3
• Switched the role attribute from "none" to "presentation", as it is closer to how the element is actually being used and has deeper support
• Documented how to integrate with MathJax, should you wish to use that were possible and this as a fallback