MathJax filter incompatible with MathJax v3.x+

MathJax has released version 3.x, which has problems with the current filter implementation:

Ref:

• https://docs.mathjax.org/en/v3.0-latest/upgrading/v2.html
• https://github.com/mathjax/MathJax/releases

In particular:

• The polyfill JS must be loaded before the MathJax JS
• You no longer call MathJax.Hub.Config(), and this function does not exist in MathJax v3.
• There's probably issues with the startup sequence, signals and queues