Migrate all frontend templates to Twig

[thorsten]

Files to be migrated to Twig:

• [ ] 404.php
• [x] add.php
• [x] ask.php
• [x] attachment.php
• [x] bookmarks.php
• [x] contact.php
• [ ] faq.php
• [x] glossary.php
• [ ] index.php
• [x] login.php
• [ ] news.php
• [x] open-questions.php
• [x] overview.php
• [x] password.php
• [x] privacy.php
• [x] register.php
• [x] request-removal.php
• [ ] search.php
• [ ] send2friend.php
• [ ] show.php
• [x] sitemap.php
• [x] sitemap.xml.php
• [ ] startpage.php
• [x] ucp.php
• [x] get rid of writecomment.php

[modelrailroader]

I would like to contribute ask.php and add.php because of the still missing forms feature implementation in the frontend.

[thorsten]

I'll start with the setup and update pages