annotation folding issues

[pierre-haessig]

Hello,

A nice folded display for annotations was introduced in #37. I noticed however three issues with the current mechanism:

1. Folding is also done in examples where annotations is the main topic, like in Experimental Conditions.
2. In Chromium 76, I can unfold, but then I cannot copy paste, because selecting the text is recognized like a click for folding
3. On Firefox Nightly 71, unfolding doesn't work. Maybe it relates to the pageview.js script loading error I see in the Firefox console:

Échec du chargement pour l’élément <script> dont la source est « https://mbe.modelica.university/_next/static/2MOgs55cIQF46eO_rXOa9/pages/pageview.js ».

Sorry I don't have right now a stable Firefox to compare with.

Best,
Pierre