add hotjar, fix exp bug, add readme, more

[vincerubinetti]

• factor out index.html metadata into env variables to avoid repetition/duplication
• add readme overview and instructions
• add hotjar analytics tracking code
• animate nav bar svg icons and rewrite logo svgs a bit to avoid conflicting css styles
• add altmetric badges for papers cited on about page
• fix critical bug where activities can change before order does and cause a crash when changing the selected experiment
• refactor tab title string construction
• move CNAME file to /public to hopefully always carry it over to gh-pages branch when deploying
• edit svgs to avoid negative dash offset bug on safari