Scroll to post in thread view when a pid is given

closes #270 (closed)

What does this MR do?

• Implements names for individual posts inside the dom so they can be referenced
• Scrolls to the specified post (by pid get parameter) when the thread is loaded

How confident are you it won't break things if deployed?

works locally.

Links to related issues

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))