This PR closes #177:

• Replaces the preCICE v1 paper with the v2 paper on the landing page.
  • Still mentions the citations to the v1 paper. On the one hand, these are currently more useful. On the other hand, Google Scholar does not seem to have listed our ORE paper yet (does it wait for citations, or does it get confused by the arXiv duplicate?). As a next step, I would add both buttons, when available (see Missing citations link/count for v2 paper #200).
  • Adds two thumbnails: one with a "new" stamp on it, one without (for later).
• Adds a "When to cite what" section in the literature guide page.
  • Refers to key references with cards from our simplistic database, as previously done for the FEniCS adapter.
  • Asks to always cite the v2 paper, still maintains a link to the v1 paper.
  • Asks to cite adapter reference papers and gives the old adapters paper for the general concept and the OpenFOAM, CalculiX, SU2, and code_aster adapters. Mentions that for OpenFOAM, there is an article in review.
  • Adds a link to the preCICE distribution to the subsection "Reproducibility"
• Adds a reference to the v2 paper in the mapping feature, as a comparison of mapping methods.
• Reworks the introduction of the literature guide to refer to the Google Scholar citations list for the v1 paper.
• Removes all the entries from the "Adapters" section of the literature guide, referring to the documentation pages of each adapter, the old overview paper, and the v2 reference paper. Also moves the link to Alex's thesis to the SU2 docs overview.
• Removes the community/publications page (also from the sidebar) and adds redirects from publications.html and the old /publications/ to the literature guide.

I did not remove the entries from our internal database, since they are actually useful. One can render any publication as a card in any page. In fact, I added a new entry for our v2 paper and reworked the entry for the old adapters overview article.

One aspect I am not sure about is if the current DOI will automatically lead or hint to the latest revision of our paper, as a second one is expected. In any case, we can just find & replace once that is needed.

@uekerman please have a look if this looks as agreed (and if there are any typos) and merge. Some screenshots to help the review:

Landing page:

Literature guide: