Ultimate preview fallback option

[Stvad]

Right now things that are not text fragments and don't allow iframe are just not rendered, but actually for anything that is not an SPA - I can use the same strategy I use now to fetch fragments (e.g. download html, inline css)

In that case almost any link becomes previeable, need to think on implication of that for:

• performance (e.g. downloading all the links in background on page load may not be a great idea)
• UX - having indicators for all link elements everywhere would probably be annoying
  • CSS selector blocklist (don't render preview for specified selectors) #13 is one potential mitigation

Configuration:

• blocklist for SPA's