Enhanced styling of `cv_entry.md`

[DunklesArchipel]

• Remove period in citation output and modify the style, i.e., author, journal, volume (year) page, Title (changed in Citation style unitpackage#152 but kept the style dictated by pybtex export, which is now properly given in the methods docstring)
• Add tags (see Improve cv overview and cv entry page descriptions #169 )
• Make download link work, i.e., build .zip package and link to it.
• Creat entry of data linked to the plot in the publication (entry linked data)
  • Link to other entries from the same publication.
• Show all curves from the same figure in the publication in a single plot at the end of cv_entry.md
  • Add a plot function to the database
  • create tab, to switch between common units used to show CVs and original units
  • Polish Style
• Create Figure with two tabs, to switch between Original axis units and the other with common units and comparable reference potential (RHE)
• Nicer printing of astropy units, i.e., in the plot
• Create collapsible curator section: Not sure if we want this. Probably it is sufficient when this information is available in the background (see Styling cv_entry.md to make it look more pleasing. #113)
• Properly render molarity in the title entry with an appropriate number of digits. (former issue Properly render molarity in the title entry with appropriate number of digits. #99 see discussion within)