DuckDuckGo clean (no history version)

Wó toś tom dodanku

Simple search plugin that uses POST method and turns r.duckduckgo.com redirects off to prevent search results pages showing up in browser history.

Enable search plugin updates and other minor changes.

Žrědłowy kod jo se pód slědujuceju licencu wózjawił: Mozilla Public License, version 2.0