Added Czech language and 404 cache evasion

[stuchl4n3k]

• Adds Czech description
• Adds optional pattern attribute to each target, which can contain following variables:
  • %YYYY --> current year (e.g. 2022)
  • %MM --> current month (e.g. 02)
  • %DD --> current day (e.g. 28)
  • %STR -> random alphanumeric string of random length (including dash -) to mimick SEO friendly words in URL
  • %NUM -> random integer up to 1e9 to mimick content ID
• Sering cached homepage is easy. Serving 404s from cache is easy. Serving unique, legit-looking 404s is hard.

[SlenkyDev]

Thank you!