added contribution section to every page

• updated zola
• added shortcode contribute
  • accepts multiple paremters (see template comment)
• added template footer
• added join us section globally in footer
• updated sidebar icons
  • better responsive behaviour
• changed paypal donation form to a standard link so it can open in a new tab
• added matomo script to footer
• added first draft for the privacy policy
  • added it to the footer
• added third party page
• added gex page

brief look: