TST Add ability to run pure python tests

MAINT Optimize the pyodide-env docker image

MAINT Allow re-creating broken symlinks under tools/

Add a package-loading version of runPython

Provide a Docker image for building

Fix iterators passed from Javascript to Python

A few impovements to benchmarks

Hotfix selenium ConnectionError issue

Handle Python long ints as Javascript floats

Fix benchmarks in light of recent changes