* migrate to esbuild from terser, since now js source needs bundling
* (temporary?) hijack inline-source object handling to inline html files
* get rid of legacy removeIf comments in source in favour of explicit
removal either through bundling tree-shaking and / or manual module-*
class element removal w/ jsdom
* get rid of multi-layered custom checkboxes in favour of
`appearance: none` directly styling the `input` elem
also removes scripting part that was supposed to adjust for=... labels
* update to html-minifier-terser, up-to-date html-minifier fork
* update to iro.js 5.5.x, using npm to manage dependencies
* build script can now update resulting html output
(called after bundling stage, before minification)
