Implement feedback from initial user tests

User testing by Katherine Rial can be found in Hedgedoc

changes for release 1.0.0

• handling of plural on views (1 view, 2 views etc)
• reconfigure link of HELMHOLTZ (on footer) to Helmholtz website https://www.helmholtz.de/en/
• make EM Glossary logo (on page headers) link to start page of EM glossary website
• bug fix in Explore page when there is no term
• search button direct to page of search results
• open all external links to new tabs in all over the project in Markdown text
  • Understanding page
  • Adapters page
  • About page
• our approach box on about page, can this bit a bit closer to the mural with two arrows?