Support for Matomo tracking

[daneov]

This PR adds the following options to Params:

• matomoUrl
  • the url where the Matomo instance can be reached
• matomoSiteId
  • the id of the site on Matomo (defaults to 1)
• matomoEnableFallback
  • Flag to enable way to track when JS is disabled
• matomoDomainPrefixed
  • Flag to prefix the tracked page with the domain
• matomoClientSideDNT
  • Flag to respect DNT header on client-side already (otherwise the request still goes to the server, where it then'll be ignored - if it respects the DNT)

P.S. This is my first encounter with Hugo's templating, if something can be done better, please suggest / correct 👍