Rewrite the web UI

[jkowalleck]

current web UI is more than 5 years old. needs to be modernized

idea: rewrite the web UI in a state of the art manner

• use pug instead of vanilla HTML
• use TypeScript instead of vanilla JS
  • try to use ES6 for the start. should be fine
• use SCSS instead of vanilla CSS
• the whole image is a single element rendered in ShadowDOM
  • if so, there mus be a possibility to still get the image URI with the browsers context menu
  • when investigating content menu manipulation, have an option to go to source?
• use modern CSS selectors
• use modern JS api to access data, style, class etc ...
• remove the maxImageSizer and use proper CSS - relative max-height/-width with vh/vw but stil keeping the aspect-ratio of the original image ...
• when writing the new web UI, put everything in a new folder src/nichtparasoup/web-ui/. compile into the usual src/nichtparasoup/_web_ui/ dir.

might come in handy:
use the DummyImage crawler from the example - it was designed to help write the web UI :-)

let webpack do the job